Milltek FAQs (Important Revisions)...

[RedRobin]

I receive a fair amount of both posts and PMs asking me specifics about Millteks on the Mk5 GTI. No problem about this....I'm flattered....But I thought it more useful to more people to share all this publicly in the forum by updating it into one post.

Trouble is that I have been misinformed (by Milltek employees, but in good faith) about the bhp increases when re-mapping is not done. I have now had chats and correspondence with Milltek's MD and consequently am updating my original post with this new one:-

EXHAUST SYSTEM:

Think of the Milltek system as having 3 components, starting at engine end first:

1) - Cat-back or Turbo-back.

2) - Resonated or Non-Resonated section.

3) - Exhaust Twinpipes or Quads exit.

Neither the Cat-back nor the Turbo-back (aka Hi-flow with Downpipe) add any significant bhp to standard [contrary to my original info] but they both subtley improve throttle response....In my experience Turbo-back more than Cat-back. The Hi-flow is so named because it is specifically designed by Milltek for turbocharged engines and, furthermore, will much more efficiently exploit any re-mapping IF done. It is obviously better to fit the exhaust first and then re-map afterwards so that the graphs are known.

Anyone intending to re-map should most definitely get the Hi-flow version. As a result of working with all the established tuners it has been Milltek's experience to date that the standard Mk5 GTI platform has got generous 'headroom' for modding up to around 250-ish bhp without any suspension or brake mods. MTM/QST, Oettinger/RSD, Abt, in particular have worked very closely with the VAG group in Germany from very early stages.

Before choosing any re-map it is strongly advised to make sure that the tuner has a map which is specifically designed for a Hi-flow and Downpipe exhaust and/or DSG and is not just based on mapping with the standard VW exhaust system.

LOUDNESS:

It so happens that my system is the loudest available with Millteks on the Mk5 GTI....Not by intention but only because of how it has evolved and this is also due in part to the generous offers I have received. If I ever thought my Turbo-back + Non-Res system was too loud for me I could then replace my Non-Res section with a new Resonated section but it potentially saves me money to continue step by step. The Res and Non-Res sections can be swopped either way.

"Do they drone?" - There is a tendency to 'drone' in the 3,200-3,500 rev band but only while those revs are held as constant without any variation. Pedalling it either way will stop the drone and it is a small price to pay for the other benefits. It's extremely easy to move away from any drone but I suppose that if you set Cruise to a speed which held 3,300 revs then you would induce droning. I personally don't like or use Cruise so I haven't tried this. I don't like anything that reduces my control of speed.

"How loud is it?" is a very subjective question I keep being asked! If you refer to the info below giving decibel comparisons you will see that no Milltek is especially loud and is better described as sporty and you can attempt to assess how it fits in with what you have already experienced (standard relative to whichever). The sound will become fractionally louder after approx 1,000 miles when the pipes 'mature'.

Standard VW exhaust = 89 dB

Milltek Cat-back + Resonated = 91 dB* (*Not tested)

Cat-back + Non-Resonated = 93.8 dB

Turbo-back + Resonated = 94.9 dB

Turbo-back + Non-Resonated = 97.1 dB

All the above, except marked*, were tested at half-metre away at 75% max revs. For Quads add 1 dB to each.

Boy-racer exhausts are probably around 110-115 dB and some louder still and are also distorted rather than a true sweet sound (like Millteks - plug, plug).

It really is extremely difficult to create accurate enough sound files which don't potentially mislead someone who is seriously considering getting Millteks.

Some approved Milltek suppliers will fit the system free of labour charges.

I'm not a qualified expert on any exhausts and am only sharing my experience with a Mk5 GTI fitted with Millteks originally as a real-world driving aid.

FURTHER INFORMATION:

Dyno graph & Technical info

[collease]

great post it actually made sense to me which is a big thing,

[Leppy]

Thanks Red,

Really appreciate this post and your in-depth knowledge in relation to the MkV. I am not very technically minded when it comes to this stuff, I just like to drive and to be honest was a bit lost in understanding some of these posts concerning this issue. But this has made it a lot clearer to me. Two questions though: It doesn't increase bhp but does improve throttle response - does this mean improves the torque or takeoff speed either at standing start or between gears so to speak? And also, what sort of money does it take to put in a system like this?

I find the Mkv a little too quiet for a sporty car but I don't like these boy racer types with extremely loud exhausts. This system seems like it has the correct mix; not too loud, but enough to let you feel the drive from the sound.

[RedRobin]

Hi Leppy, your post made me smile because before I ordered my Mk5 GTI and discovered TSN I knew absolutely diddlysquat about anything technical on the GTI or any other car! I'm not especially technically minded either so I try to present information as non-technically as possible. To answer your questions:

1) - I don't think that torque is improved or "take-off speed". Just that you feel the power respond to your foot pressure on the the throttle pedal more quickly than without Millteks.

2) - Costs? It's best you contact Milltek or check their web site and find an approved supplier and installer. Some will fit free of charge if they supply you the Millteks.

You are absolutely right - the Milltek system "has the correct mix". Be absolutely assured that even the loudest Non-Resonated Turbo-back exhaust is nothing approaching 'boy-racer' loudness....More like a standard sports car. It really does work as a real-world driving aid.

If you plan to ever re-map then get a Hi-flow, otherwise a Cat-back. If you do a lot of constant rev driving (around 3,200) due to Motorways and also listen to music while you are doing so, then get Resonated. If you like it just fractionally sportier and drive lots of twisties etc, get Non-Resonated.

Where are you located? PM me if you don't wish to publish where.

[Leppy]

Cheers for the reply Red.

It's good to know I'm not the only one around that knows how to drive a car, but hasn't a clue how they work except for petrol and oil!!!

I'm in Ireland. Due to pick up my Red MkV in 2 weeks and just from driving them, I just expected it to have a little more bite in the sound department, but found it was just a little too quiet for me for what I was driving. The system you describe above sounds exactly what I'm looking for. I see a lot of local guys here that get exhausts done, and they're just way too loud. I like a pleasaant mix of sportiness without been heard a mile away. I think Resonated is the one for me.

[RedRobin]

I know from their MD that Milltek's majority of GTI sales are overseas so you shouldn't have a problem. You can see that depending on whether Cat-back or Turbo-back you are looking at only 4-5 dB louder than standard and that's roughly only 0.06% louder than standard!!

The main reason that the stock exhaust is quiet is due to too effective soundproofing in the cabin. A lot of modern cars suffer from this, and I have even heard of gizmos on the market that imitate an exhaust sound inside the car!!!! YeeuuukkK!!!! I have also read that the left-hand drive Mk5 GTIs are a tad louder - I expect Snoopy might know why.

I think it's "Barry_Twomey1980" who's got Millteks on his GTI in Ireland....PM him if you can't attract his attention here.

[mainy]

Great post Red

But can you please stop putting information about modding on here as it will have a serious effect on my bank balance

[martininwillerby]

Hi RED.....Plain and simple,Would fitting a back box only improve performance,acceleration or top speed....if not would Milltek confirm this in writing so I then could take it to my insurer for approval and then fitment.....

[martininwillerby]

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http://www.thettshop.co.uk/milltek.pdf

[martininwillerby]

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[martininwillerby]

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[RedRobin]

If I have understood your question correctly, you cannot fit only a "back box". You have to replace the stock exhaust with the components I have numbered 1/2/3 in my post above. Your only choices are which Milltek components you use, but all three must all be Milltek for the system to work and also be guaranteed. You can later substitute one Milltek component for another Milltek component, again as I have explained above.

None of these components significantly increase the performance unless you have your car re-mapped, although there is a slight improvement in throttle response as I explained above.

As there is no power increase you do not have to pay extra insurance premiums for that aspect but only for the equipment itself, probably in the form of increased excess. All you might need for your insurer is proof of installation, i.e. sales receipt in the event of a subsequent claim. Some insurance companies will not insure a modded car at all unless they already know you.

I hope I have answered your questions, or have I got the wrong end of the stick?

[AliJay]

[ QUOTE ]

I know from their MD that Milltek's majority of GTI sales are overseas so you shouldn't have a problem. You can see that depending on whether Cat-back or Turbo-back you are looking at only 4-5 dB louder than standard and that's roughly only 0.06% louder than standard!!

[/ QUOTE ]

Sorry to say I think you've got your maths a wee bit wrong, an increase from 89db to 94db represents an increase of just under 6%, not 0.06% as stated.

Additionally, from my limited understanding of measuring sound I don't believe you can simply compare db readings in the way you suggest. I'm sure you will find that an increase from 89db - 93.4db represents far greater increase of perceived (physical) volume than 5% - db measurements aren't proportionate in the way you imply, an increase of 6db is a doubling of volume.

Furthermore, why on earth you would want to fit an exhaust that drones at 80-88mph is totally beyond me. I believe everyone would agree this is the typical speed modern day Motorway traffic travels at.

[RedRobin]

Thank you for correcting my calculations on the comparitive dB levels. Nevertheless having experienced all these exhaust configurations I can only assure everyone that in my opinion the sound differences as heard by the driver are only slight and nowhere near the levels of 'boy-racer'. It's certainly much quieter than an Impreza, as a point of reference for you.

I personally don't find a continuous engine sound at 3,200-3,400 (usually less than 80-88 mph running in DSG D-mode) to be a problem. I appreciate that others might and that's partly why I am giving information as best and fully as I can. It's no louder than a sports car. As I wrote earlier: "If you do a lot of constant rev driving (around 3,200) due to Motorways and also listen to music while you are doing so, then get Resonated. If you like it just fractionally sportier and drive lots of twisties etc, get Non-Resonated."

Ultimately people have to make up their own minds and sound is a very subjective topic. All I can do is share what I find out and offer my opinion.

[RedRobin]

Thanks for posting the links, Martin

[AliJay]

[ QUOTE ]

I personally don't find a continuous engine sound at 3,200-3,400 (usually less than 80-88 mph running in DSG D-mode) to be a problem.

[/ QUOTE ]

Glad to be of assistance to the discussion.

For fear of sounding a tad pedantic, every car makes a continuous engine sound at a given RPM. The word you used before was "drone" which is an entirely different thing and IMO is unacceptable at any speed in a road car.

I can well believe that a Hi-flow system will improve throttle response as it will help the turbo spool up faster. Additionally any increase in BHP will be barely discernible unless you also go for a re-map & take full advantage of the engines improved breathing. That said, you might also find you need to change the air filter & induction hoses to get the maximum benefit & possibly even up-rate the fuel pump depending on it's capacity - to ensure the engine doesn't run lean & burn the top out of the pistons.

From my experience of having my Impreza tweaked I am fully aware of the amazing transformation that can be had with next to no detrimental effects to rest of the car. In my case it's made the car one hell of a lot faster & more drive-able in everyday use, with no appreciable increase in engine noise (I went for the quietest performance exhaust system I could find) or, even more remarkably, it's thirst for Optimax.

As I drive a MkV GTI & an Impreza (which has possibly the most evocative sound track of any 4 cylinder car on the market today) I can quite understand the reasons why anyone would want to enhance the exhaust note of a MkV because as standard it doesn't really do the cars sporting credentials justice, especially when you're driving it with a heavy right foot, but hey everything in life is a compromise.

Just out of interest what sort of improvements in bhp & torque are you talking about if you go for a turbo back Milltek & a remap?

[RedRobin]

Hi again, AliJay....

Yes you are of course right about continuous sounds. Sound is a very difficult thing to put into words but my use of the word "drone" just means continuous at a loudness which some people may find unacceptable inside the car but which I don't. I probably would find it unacceptable if I was trying to listen to classical or quiet music on a motorway while holding around 3,200 revs which is the level at which the GTI seems loudest internally.

As I'm running my GTI with Hi-flow (Turbo-back) but no re-map, I'm very interested in what you have said: "....you might also find you need to change the air filter & induction hoses to get the maximum benefit & possibly even up-rate the fuel pump depending on it's capacity - to ensure the engine doesn't run lean & burn the top out of the pistons." I'm hoping that this doesn't mean that I'm likely to do this unless I re-map or start other engine mods which I am reluctant, out of my ignorance, to do.

It seems that with the Turbo-back Milltek fitted, most tuners are using re-maps which result in around 265-275 bhp, but some are not without problems - hence my holding back. Torque also increased but I don't know the stats - TSN Tuning forum would hold such info.

Personally I would prefer a custom tune and only about 245-250 bhp with appropriate torque.

Cheers,

[AliJay]

[ QUOTE ]

Hi again, AliJay....

Yes you are of course right about continuous sounds. Sound is a very difficult thing to put into words but my use of the word "drone" just means continuous at a loudness which some people may find unacceptable inside the car but which I don't. I probably would find it unacceptable if I was trying to listen to classical or quiet music on a motorway while holding around 3,200 revs which is the level at which the GTI seems loudest internally.

As I'm running my GTI with Hi-flow (Turbo-back) but no re-map, I'm very interested in what you have said: "....you might also find you need to change the air filter & induction hoses to get the maximum benefit & possibly even up-rate the fuel pump depending on it's capacity - to ensure the engine doesn't run lean & burn the top out of the pistons." I'm hoping that this doesn't mean that I'm likely to do this unless I re-map or start other engine mods which I am reluctant, out of my ignorance, to do.

It seems that with the Turbo-back Milltek fitted, most tuners are using re-maps which result in around 265-275 bhp, but some are not without problems - hence my holding back. Torque also increased but I don't know the stats - TSN Tuning forum would hold such info.

Personally I would prefer a custom tune and only about 245-250 bhp with appropriate torque.

Cheers,

[/ QUOTE ]

Hi Red

Thanks for clarifying what you meant by drone, I quite agree that it's virtually impossible to describe sound quality/levels and I have to admit my interpretation was straying more towards exhaust boom rather than constant tone/volume.

Whilst there's always a risk when you start modifying engines beyond the manufacturers original specification, from what I've learned I doubt you'll have any problem with just an exhaust upgrade, but once you start on remapping & are able to use more boost & increase thermal stresses that's when you start getting into silicon (Samco et-al) hoses and up-rated fuel pumps. The problem with the fuel pump on modified engines is that the ecu will demand more fuel in order to keep mixtures in the cylinders correct. If the pump cannot supply enough fuel then the mixture will go lean and pre-detonation can occur, with potential risk of damage to valves and pistons. Silicon hoses is to improve air flow & stop them from balloning & splitting

There is no doubt that once you enter the world of remapping you are very much in the hands of the man that "crunches the numbers". In the case of my Impreza I went to a man with World Rally Championship winning credentials and someone in the Scooby community that has a very good reputation for knowing how to extract more power without compromising reliability.

The gains I got with a Samco induction kit (air box to inter-cooler, inter-cooler to throttle body & boost recirculating hoses), Green air filter, de-cat up-pipe, thundercat (100 cell sports cat) down pipe, de-cat middle, Prodrive WR Sport rear box (basically the system internally & externaly is as quiet, if not quieter than a Group N rally car) & an Ecutek remap were in the region of 30% more bhp & torque. In real terms this translates into a wider power band (lots of useable power from 2750 - 6500rpm) with next to no histrionics - banging & popping, boom or drone.

Personally I didn't want to get into bigger turbos and upgraded transmissions (& there are lots that do), I simply wanted to get some extra power & improve the all round drivability of the car. However, as you have said before, once you start on the path of modding it's very hard to stop, you're always tempted to go to the next stage & the next stage & the next stage.................now where did I put my cheque book.

Have a look on http://www.scoobynet.co.uk/ if you'd like to find out more about what Scooby drivers are up to, it's nearly as good as Tyresmoke.

So far as increasing the power output of GTI's go, I think the limiting factor is the traction available and how much power the front wheels can transmit to the road in every day driving.

[RedRobin]

[ QUOTE ]

So far as increasing the power output of GTI's go, I think the limiting factor is the traction available and how much power the front wheels can transmit to the road in every day driving.

[/ QUOTE ]

....I couldn't agree more! Everyday driveability and reliability are all important and any performance mods need to respect that imo. Consequently I am taking my time and will not re-map until/unless I feel 100% confident. I have upgraded the exhaust system primarily to allow me to better hear the engine as a driving aid and only secondarily to give me the possibility of a future re-map option, and I am about to upgrade the suspension. Your information is helpful and confirms the wisdom of holding back. Afterall, the GTI has been very well designed and doesn't need much fiddling about with.

Thanks,

Robin

[RedRobin]

Just a bit more info....

Fitting the Milltek Hi-flow (Turbo-back) + downpipe may possibly add just a few (4 or 5) bhp to a stock, not re-mapped GTI Mk5 and should fractionally increase turbo spool speed as well as throttle response as already reported. All very subtle and nothing earth-shattering!

Fitting a Turbo-back system before rather than after a re-map, as Jay and I have done, appears to be quite unusual but doesn't matter.

[mb]

[ QUOTE ]

Additionally, from my limited understanding of measuring sound I don't believe you can simply compare db readings in the way you suggest. I'm sure you will find that an increase from 89db - 93.4db represents far greater increase of perceived (physical) volume than 5% - db measurements aren't proportionate in the way you imply, an increase of 6db is a doubling of volume.

[/ QUOTE ]

Decibels are a log scale, an increase of 10 decibels will result in 10x the sound intensity, a 20 decibel increase would be 100x louder !

[AliJay]

[ QUOTE ]

[ QUOTE ]

Additionally, from my limited understanding of measuring sound I don't believe you can simply compare db readings in the way you suggest. I'm sure you will find that an increase from 89db - 93.4db represents far greater increase of perceived (physical) volume than 5% - db measurements aren't proportionate in the way you imply, an increase of 6db is a doubling of volume.

[/ QUOTE ]

Decibels are a log scale, an increase of 10 decibels will result in 10x the sound intensity, a 20 decibel increase would be 100x louder !

[/ QUOTE ]

Thanks for the confirmation of what I was saying about db's & their effect on actual volume levels.

[RedRobin]

[ QUOTE ]

[ QUOTE ]

[ QUOTE ]

Additionally, from my limited understanding of measuring sound I don't believe you can simply compare db readings in the way you suggest. I'm sure you will find that an increase from 89db - 93.4db represents far greater increase of perceived (physical) volume than 5% - db measurements aren't proportionate in the way you imply, an increase of 6db is a doubling of volume.

[/ QUOTE ]

Decibels are a log scale, an increase of 10 decibels will result in 10x the sound intensity, a 20 decibel increase would be 100x louder !

[/ QUOTE ]

Thanks for the confirmation of what I was saying about db's & their effect on actual volume levels.

[/ QUOTE ]

....So for the benefit of those of us without a science degree, will one of you please post what percentage louder 97 dB is above the standard 89 dB. Many thanks

[jcull]

Since 10 dB equates to a x 10 increase, every 3.16 dB (i.e. the square root of 10) the loudness of the sound doubles.

Jeremy

[AliJay]

[ QUOTE ]

...So for the benefit of those of us without a science degree, will one of you please post what percentage louder 97 dB is above the standard 89 dB. Many thanks

[/ QUOTE ]

Hi Red, have a look at this stite http://www.practicalpc.co.uk/computing/sound/dBeasy.htm, it might help explain things.