Exhaust options: more "growl" but not too loud?

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sync24
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Re: Exhaust options: more "growl" but not too loud?

Post by sync24 » Wed Jan 23, 2013 9:54 am

Rick_RS4 wrote:you didnt spend stupid money for miltek which is just the same exhaust with less baffles in the cans.
Wow - that's a damning statement :shock: I am planning on a valved non-res milltek in the summer - surely they must have put some research into improving on the OEM Unit? Mind you I do expect Audi did engineer the exhaust well..... If it's just a case of some baffle replacements then I will go down that route as the Milltek aint cheap :roll:

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Re: Exhaust options: more "growl" but not too loud?

Post by STURS4 » Wed Jan 23, 2013 12:04 pm

TonyHayers wrote:
MikeFish wrote:Or did you mean the grill? You must have really clouted it to go through the grill and damage the speaker!
Yeah, might just be the grill -will check it out in the morning. Freakin hurt tho, right on my ass. Did that thing where you look around to make sure nobody was looking, but was in a country park miles from anywhere thankfully.

Btw, I never noticed the exhaust flaps make that opening/shutting noise before (don't spend a lot of time stood behind my own car). I just thought the vacuum actuator pulled them open and that was that until they closed again. Wonder if I do have some sort of vac leak :s
Sounds great mate,think i might have to get that done.your exhaust flaps make that noise anyway,it is quite noticeable.Ive done the flapper mod so it keeps the flaps open at all times,really easy to do.

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sonny
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Re: Exhaust options: more "growl" but not too loud?

Post by sonny » Wed Jan 23, 2013 1:08 pm

But the Milltek has, near OEM looks, keeps the valve functionality and has a lifetime warranty to original owner. They might not be the best exhaust system in the world but are fit for purpose for the RS4. Only downside is the drone (after a few years)
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Re: Exhaust options: more "growl" but not too loud?

Post by Timster » Wed Jan 23, 2013 1:15 pm

Second clip sounds better Tony.

You could either lube the valve actuators with copper-grease etc (they sell it in halfords).
Or just remove the vacuum lines and plug them with a slightly oversized wood-screw.
Temporary, (if you want), very quick.... but very effective.
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Re: Exhaust options: more "growl" but not too loud?

Post by Rick_RS4 » Wed Jan 23, 2013 1:54 pm

sync24 wrote:
Rick_RS4 wrote:you didnt spend stupid money for miltek which is just the same exhaust with less baffles in the cans.
Wow - that's a damning statement :shock: I am planning on a valved non-res milltek in the summer - surely they must have put some research into improving on the OEM Unit? Mind you I do expect Audi did engineer the exhaust well..... If it's just a case of some baffle replacements then I will go down that route as the Milltek aint cheap :roll:

Yes it is, the original cats are good if not better than the aftermarket ones but you will need to gut the pre cats, to get the same gains, if filter were marketing a performance exhaust why didn't they enlarge the bore and fit either an x or h pipe in? There has been many tests in the states to show how good the original system is compares to some aftermarket exhausts.

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Re: Exhaust options: more "growl" but not too loud?

Post by TonyHayers » Wed Jan 23, 2013 4:20 pm

Timster wrote:Second clip sounds better Tony.

You could either lube the valve actuators with copper-grease etc (they sell it in halfords).
Or just remove the vacuum lines and plug them with a slightly oversized wood-screw.
Temporary, (if you want), very quick.... but very effective.
Cheers Tim, got some - will give it a shot.
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Re: Exhaust options: more "growl" but not too loud?

Post by TonyHayers » Wed Jan 23, 2013 4:30 pm

P_G wrote:The way taken in those pics is supposedly quicker / easier. Reduced cross over area for scavenging but like said if it works....
Btw, I reckon you're right P_G, there's no way I can see (I'm not a flow engineer of course!) that this *particular* implementation of an x-pipe can generate any power - if anything it seems like it might lose power! Looking at my x-pipe compared to stock resonators the stock has a much smoother flow path. It seems logical that a smoother curve and larger crossover area where they meet would assist scavenging?

Surely, if the angle where the two pipes meet is too steep, the exhaust pressures from each side are going to "bump" into each other (giving some back pressure?) rather than smoothly join together and assist with draw.
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DONE: Water Meth Injection, Carbon clean at 64k, CAI, Gutted Precats, Non-res x-pipe, H&R 8mm spacers, H&R springs
^ GONE :cry:

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Re: Exhaust options: more "growl" but not too loud?

Post by P_G » Wed Jan 23, 2013 5:25 pm

Rick_RS4 wrote:
sync24 wrote:
Rick_RS4 wrote:you didnt spend stupid money for miltek which is just the same exhaust with less baffles in the cans.
Wow - that's a damning statement :shock: I am planning on a valved non-res milltek in the summer - surely they must have put some research into improving on the OEM Unit? Mind you I do expect Audi did engineer the exhaust well..... If it's just a case of some baffle replacements then I will go down that route as the Milltek aint cheap :roll:

Yes it is, the original cats are good if not better than the aftermarket ones but you will need to gut the pre cats, to get the same gains, if filter were marketing a performance exhaust why didn't they enlarge the bore and fit either an x or h pipe in? There has been many tests in the states to show how good the original system is compares to some aftermarket exhausts.
Not strictly true because the type of metal used, pipe diameter / length and flow path also have a lot to contribute. That's why some people like titanium exhausts because they give a more unique note. Most Audi exhuausts are made of type 302 steel where as after markets use Type 204 which gives a different sound. Pipe diameter also differs, most aftermarket are 2.5" and aboove and OEM is 2.25" (but then this is the big factor in resonance drone) and then there are the baffles and the shape / internal area of the silencers. Not doubting OEM exhausts are good but there is some justification in the price of aftermarket exhausts in material quality and design.

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Re: Exhaust options: more "growl" but not too loud?

Post by sakimano » Thu Jan 24, 2013 5:48 am

sar wrote:i echo what PG said, i would be surprised about any gain in hp it certainly wouldn't be measurable on a dyno.
the best full exhaust system out there for the rs4 might get you 20-25hp.
X pipe gains can be significant (but not where that one is...!!!)

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Re: Exhaust options: more "growl" but not too loud?

Post by sakimano » Thu Jan 24, 2013 5:50 am

TonyHayers wrote:
Timster wrote:Indeed it does. Maybe theres' some reasoning behind that method, but wouldn't two formed-cut, then spliced&welded together sections, have been easier and more effective ?
Yeah, I was a little disappointed since they said it would be like this, which *looks* far more elegant and freer flowing...
mmfp_0708_11_z+2006_ford_mustang_GT_exhaust_install+X_pipe.jpg
P_G wrote:If they have a proper mandrel bending machine it should be ok and no indentations but that looks more like four sections TIG welded to a middle pipe section? But if it does the job then ideal. Do you get any throttle lift off / clutch ride exhaust burble / popping?
Yeah, seems to be a bit of burble/popping on throttle lift off. In terms of cabin volume it's a fair bit louder when given a bit of welly :) at more sedate pace there's a bit of drone under load in high gears at around 1500 to 2000 rpm - but not too bad. I'd say valves closed with this x-pipe is something like 30% louder than stock resonators with valves open. So far it feels just about right in terms of cabin noise.

I'll try and get a video done at lunch time.
The one in the pics looks like the magnaflow box x

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Re: Exhaust options: more "growl" but not too loud?

Post by Rigsby1208 » Mon Jan 28, 2013 1:12 pm

I'm looking for a bit more growl as well, but without any drone. From what I've seen it looks like cross pipes are the cheapest appropriate path or have I missed something? Secondly does anyone have a diagram showing the original exhaust system and what bits people change and names of the sections? I know its an ask, but get confused with all the different terminology and what people are actually talking about!

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Re: Exhaust options: more "growl" but not too loud?

Post by TonyHayers » Mon Jan 28, 2013 5:20 pm

Rigsby1208 wrote:I'm looking for a bit more growl as well, but without any drone. From what I've seen it looks like cross pipes are the cheapest appropriate path or have I missed something? Secondly does anyone have a diagram showing the original exhaust system and what bits people change and names of the sections? I know its an ask, but get confused with all the different terminology and what people are actually talking about!
The crossover/x-pipe that I had fitted replaced the stock centre silencer (a.k.a "resonators"). The centre silencer (on stock cars) sits across both pipes between the backboxes (a.k.a "mufflers" or "rear silencers") and the main catalytic converters (a.k.a "main cats"). Non-resonated systems, such as the Milltek non-res systems, often just have straight pipes ("straight" as in it's just pipe, not that it's necessarily in a straight line) from the main cats through to the back boxes.

The photo below shows the stock cat-back (on the left) compared to a non-resonated Milltek (I think?) aftermarket system. These are the cat-back systems i.e everything after the cats...
DSC_0006a.jpg
HTH. Feel free to correct me anyone :)
06 Phantom Black Saloon:
DONE: Water Meth Injection, Carbon clean at 64k, CAI, Gutted Precats, Non-res x-pipe, H&R 8mm spacers, H&R springs
^ GONE :cry:

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Re: Exhaust options: more "growl" but not too loud?

Post by Rigsby1208 » Mon Jan 28, 2013 5:32 pm

Ok a bit clearer. So working towards the engine from the pipes in the diagram there would be the main cats then the pre cats?

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Re: Exhaust options: more "growl" but not too loud?

Post by TonyHayers » Mon Jan 28, 2013 5:42 pm

Rigsby1208 wrote:Ok a bit clearer. So working towards the engine from the pipes in the diagram there would be the main cats then the pre cats?
Yep.
06 Phantom Black Saloon:
DONE: Water Meth Injection, Carbon clean at 64k, CAI, Gutted Precats, Non-res x-pipe, H&R 8mm spacers, H&R springs
^ GONE :cry:

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Re: Exhaust options: more "growl" but not too loud?

Post by joesnow » Mon Jan 28, 2013 9:04 pm

Need to cross it of your to do list Tony.
Current: 2010 A6 2.0 TDi
Gone: 2006 B7 RS4 Avant

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