Milltek exhaust for s4

[Spearo]

So the S4 needs more noise !
When I’m out of warranty I’ll be putting on a new exhaust and remapping.

There don’t seem to be too many options out there at the moment so currently milltek looks like the main option (and not a bad one really).
Obviously I’d want the unresonated option, to maximise noise, but thinking about tuning too, my question really is ..... how restrictive is the standard cat and down-pipe? Would a full system (turbo back) be necessary or will a cat back system give noise and options for more power?

Anyone got any thoughts?

 

[Daggerit]

So the S4 needs more noise !
When I’m out of warranty I’ll be putting on a new exhaust and remapping.

There don’t seem to be too many options out there at the moment so currently milltek looks like the main option (and not a bad one really).
Obviously I’d want the unresonated option, to maximise noise, but thinking about tuning too, my question really is ..... how restrictive is the standard cat and down-pipe? Would a full system (turbo back) be necessary or will a cat back system give noise and options for more power?

Anyone got any thoughts?

I’ve got the non res cat back and it’s far better than OEM. Plenty pops and burbles.

I haven’t heard any with the downpipe fitted I’m afraid but at £1300 for the sports cat version I’m happy with just the cat back right now. Personally I’d start with that and see how you get on because the down pipe can be added later no worries.

Mine:




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[Riko0073]

So tempted by the Miltek, sounds great.

AWE switchpath also good but over £3k that’s a lot of money!

@Daggerit does the Miltek still work with the different drive modes i.e quiter in comfort etc and then louder in dynamic/sport?

 

[Daggerit]

So tempted by the Miltek, sounds great.

AWE switchpath also good but over £3k that’s a lot of money!

@Daggerit does the Miltek still work with the different drive modes i.e quiter in comfort etc and then louder in dynamic/sport?

Yeah it does. The quiet modes are about the same as OEM but with all the valves fully open. The loud mode gives almost straight through, but it’s still not obnoxiously loud as to annoy people miles away.


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[Thundercliffe81]

I’ve got the non res cat back and it’s far better than OEM. Plenty pops and burbles.

I haven’t heard any with the downpipe fitted I’m afraid but at £1300 for the sports cat version I’m happy with just the cat back right now. Personally I’d start with that and see how you get on because the down pipe can be added later no worries.

Mine:




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That sounds so much better than stock. Haha. Downshifts are good.


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[Spearo]

Does exhaust fitting invalid warranty or are you guys refitting the standard exhaust before service or warranty claims ?

Coming from a JDM import Subaru Legacy (without any warranty)the S4 is super quiet !

 

[Riko0073]

Yeah it does. The quiet modes are about the same as OEM but with all the valves fully open. The loud mode gives almost straight through, but it’s still not obnoxiously loud as to annoy people miles away.


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Right I’m sold!!

 

[Daggerit]

Does exhaust fitting invalid warranty or are you guys refitting the standard exhaust before service or warranty claims ?

Coming from a JDM import Subaru Legacy (without any warranty)the S4 is super quiet !

Took mine in for warranty work and they never said anything about the exhaust. Apart from asking for some revs!


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[Thundercliffe81]

Took mine in for warranty work and they never said anything about the exhaust. Apart from asking for some revs!


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All about having a good dealer. Mine got excited because I've took the valve plugs out. Unreal haha.


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[WesT-gefül]

Sounds good with that cat back system. Even with a sport cat would it pass the new MOT?

 

[Daggerit]

Sounds good with that cat back system. Even with a sport cat would it pass the new MOT?

As far as I’m aware it will, that’s the reasoning behind getting one instead of a decat. Don’t quote me on it though.


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[Daggerit]

All about having a good dealer. Mine got excited because I've took the valve plugs out. Unreal haha.


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That’s not cool. I can’t imagine they’d class the exhaust system as being under warranty so I don’t know how they could justify voiding warranty either...


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[Thundercliffe81]

That’s not cool. I can’t imagine they’d class the exhaust system as being under warranty so I don’t know how they could justify voiding warranty either...


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They can only void the parts directly involved. Glad they've changed that.


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[Daggerit]

They can only void the parts directly involved. Glad they've changed that.


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Yeah, or that they can link to the issue (although that’s directly involved I guess...). Can’t see an exhaust system managing to cause any issues to anything at all.


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[Thundercliffe81]

Yeah, or that they can link to the issue (although that’s directly involved I guess...). Can’t see an exhaust system managing to cause any issues to anything at all.


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There's a very very simple fix that BMW and AMG seem to be doing well at. Offer performance based aftermarket parts from the dealer. That way they meet EU 'standards' and satisfy us that are hungry for more. Profit win win. Warranty intact. And not just a £6k Akrapovic system haha.


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[Daggerit]

There's a very very simple fix that BMW and AMG seem to be doing well at. Offer performance based aftermarket parts from the dealer. That way they meet EU 'standards' and satisfy us that are hungry for more. Profit win win. Warranty intact. And not just a £6k Akrapovic system haha.


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That would be nice!


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[Spearo]

So looking at the milltek cat back or just downpipe options, it looks like their systems are compatible with the standard system on the car - which I assume is resonated.
My question to those who have milltek is - are pipe diameters any different to standard ?
My other thought, if the systems (milltek and standard) have similar size pipes, would a resonator delete with the standard system give reasonable sound results?
Does anyone have a picture of the standard system??? Google isn’t helping me today !

 

[Daggerit]

So looking at the milltek cat back or just downpipe options, it looks like their systems are compatible with the standard system on the car - which I assume is resonated.
My question to those who have milltek is - are pipe diameters any different to standard ?
My other thought, if the systems (milltek and standard) have similar size pipes, would a resonator delete with the standard system give reasonable sound results?
Does anyone have a picture of the standard system??? Google isn’t helping me today !

The pipe diameters are not the same, the Milltek system is 2.5” the whole way from the downpipe and the OEM is 2” or 2.25” and crimped down in places and at bends.

The standard system has one resonator on each pipe just after the downpipe and then they both go into a central resonator then onto the back boxes. I know people that deleted the small individual resonators and the central one and found that it drones badly. Just the central one would make a significant difference as the back boxes are actually really small on the S4.

My OEM system is in the shed but would take some serious digging to get a photo so I’ll see if there’s some in my thread I can pop in here.

Found photos of the stock system I took while I was down at Milltek but for some reason the app won’t let me upload them. They’re in post #139 of my thread though - ‘Dan’s S4 thread’. Or something to that effect, can’t remember the exact name of it. Hope that helps a bit!


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[Spearo]

Awesome- thanks Dan
This is good to know ! You clearly are veritable mine of information.... thanks !

 

[Daggerit]

Awesome- thanks Dan
This is good to know ! You clearly are veritable mine of information.... thanks !

I wouldn’t go that far, just some info from being there when they built my system and asking way too many questions.


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[motty225]

The pipe diameters are not the same, the Milltek system is 2.5” the whole way from the downpipe and the OEM is 2” or 2.25” and crimped down in places and at bends.

The standard system has one resonator on each pipe just after the downpipe and then they both go into a central resonator then onto the back boxes. I know people that deleted the small individual resonators and the central one and found that it drones badly. Just the central one would make a significant difference as the back boxes are actually really small on the S4.

My OEM system is in the shed but would take some serious digging to get a photo so I’ll see if there’s some in my thread I can pop in here.

Found photos of the stock system I took while I was down at Milltek but for some reason the app won’t let me upload them. They’re in post #139 of my thread though - ‘Dan’s S4 thread’. Or something to that effect, can’t remember the exact name of it. Hope that helps a bit!


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I think I'm going to go with removing the center resonator and seeing how it is with that to start with

 

[Daggerit]

I think I'm going to go with removing the center resonator and seeing how it is with that to start with

If it can be removed such that it could be put back in if needed then you’re not missing out on anything by trying it! You’ll have to let us know how you get on.


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[Daggerit]

Sounds good with that cat back system. Even with a sport cat would it pass the new MOT?

I believe so, but don’t quote me on that!


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[motty225]

If it can be removed such that it could be put back in if needed then you’re not missing out on anything by trying it! You’ll have to let us know how you get on.
Yeah that's the plan as it's a lease, if it can be removed and then clamped instead of welding, then there is no harm in trying it

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[WesT-gefül]

Here is a good video. Stock vs resonated Milltek vs non resonated Milltek



Much prefer the resonated Millltek which isn’t too loud.

 

[Daggerit]

I can't speak for the 2.0T systems, but with the S4 systems the resonated is very close to stock in terms of the actual volume (as measured). I can't comment how it sounds in person because they didn't have a car with one on it whilst I was there but I'd imagine that it's a deeper sound with a few more burbles and overall a similar volume.

In comparison, the non-res version is something like 5 or 10db louder I believe. If my memory serves correctly, at idle the figures were something like 84db OEM, 83db resonated and 91 or 93 non-res and the constant revs had the same sort of comparative gaps but with the resonated a little louder than the OEM. Only a couple db though I seem to recall. That's why I went for the non-res.

 

[Boosted_Six]

The standardized test for track days etc was always half meter distance @ 3/4 of max revs. Anything under 95db is pretty civilized

 

[Spearo]

So it looks like the milltek unresonated cat back isn’t EC approved. In 18 months time is a car with this fitted going to pass an MOT ?

Also, I’m wondering how durable the finnishes are on the milltek- the ceracote and the burnt titanium in particular- can they be scrubbed without taking off the finish ? I ask because my last milltek had a simple polished tip and I used wire wool to clean that .... can I do the same with the two above finnishes?

 

[Daggerit]

So it looks like the milltek unresonated cat back isn’t EC approved. In 18 months time is a car with this fitted going to pass an MOT ?

Also, I’m wondering how durable the finnishes are on the milltek- the ceracote and the burnt titanium in particular- can they be scrubbed without taking off the finish ? I ask because my last milltek had a simple polished tip and I used wire wool to clean that .... can I do the same with the two above finnishes?

Provided the emissions are alright I can’t see there being any issue because it’s not ridiculously loud.

I don’t know about the finishes for sure, I’d imagine the titanium one would be fine to wash however (because the finish is as a result of the material changing colour when heated), but I don’t know about the ceracote ones. I’d give Milltek a shout to be honest, I need to do the same for my brushes titanium ones to see the best way of cleaning them now that they’re getting a bit grimey.


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[Spearo]

But on the milltek website it claims that the resonated systems are EC pending - you think the EC approval is noise related ? I was under the impression that it would’ve been emissions that were scrutinised and having a resonator or not shouldn’t impact the emissions - should it !?! I wouldn’t have thought so !

 

[Spearo]

I’ll phone them tomorrow and find out !

 

[Daggerit]

But on the milltek website it claims that the resonated systems are EC pending - you think the EC approval is noise related ? I was under the impression that it would’ve been emissions that were scrutinised and having a resonator or not shouldn’t impact the emissions - should it !?! I wouldn’t have thought so !

I’m thinking it’s noise related because the cat back system retains all the original emissions stuff, I.e. the cats. We’re fine here in the UK I’d say, I’ve put cars through with louder exhausts so long as the emissions are within the limits.


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