EXHAUST RECOMENDATIONS

[WRS4]

I would like to add a exhaust to my rs4 b7, i know these are not cheap but being a family man i cant justify throwing cash at one either so i guess putting on full race systems ect ect is not really for me, THAT SAID, i do want the car to sound pretty loud.

So being new to audi (bmw m3 man) can some one please advise on whats best for the following:

1. ideal make, i know milltek is a good one but over £1000 just for the back box, if thats what it takes ok but was hoping that some of you have tried others and are please with the sound.

2. resinated / non resinated ? i assume this means non resinated is louder ? and if so is this the best choice ?

3. valved / non valved ? again i assume pressing the sports mode opens the valve so is it best to have non valved ass i am heavy footed lol

4. will just replacing the back box / pipes give me good sound ? as i dont want to spend out only to find a small difference, for example i fitted an eismann race back box to my m3 a few years back and didnt touch anything else and the sound was amazing.

5. any other advice welcomed

cheers

[coffey555]

Just remove the centre silencers and replace with straight pipes for around £200.

Then disconnect the vaccum hoses to the exhaust flaps and plug them with a pair of golf tee's.

Loud but not too loud apart from on a cold start up.

You will have one of the best sounding exhaust notes on the road today.

[MikeFish]

As above. I spent thousands on exhaust for the B7 and ended up with this.

[jonytek]

I would also recommend gutting the precats, this made a big difference. I was disappointed with just cutting the center res out. I think I paid a couple of hundred quid for the precats at AMD, MRC charge double that.

[Starry]

I would also recommend gutting the precats, this made a big difference. I was disappointed with just cutting the center res out. I think I paid a couple of hundred quid for the precats at AMD, MRC charge double that.

You will need to map or use spacers on the lamdba to stop throwing a fault.

[WRS4]

ok i have to play dumb here,,,,, i have no idea what your all going on about as i say i have never come across all this before and on the m3 just threw on an eismann so bare with me.

SO PLEASE CONFIRM I HAVE ALL THIS:

1. their are two center silencers on this car, and i need to go to a garage, get these cut out and straight pipe work added ???? is that right ? and more to the point is it legal / m.o.t friendly ? are these what are known as resonators ?

2.remove the vacum hoses ?? what the hell are they lol and just plugging them is that not a bit of a bodge job or totally ok ?? so what happen to the exhaust flap end where i remove the pipe from ? does this just get let unsealed ?

3. i have no idea what pre cat means, and if its going to cause issues with codes ect then maybe best i dont bother but will it still sound good ? i would like a nice roar but nothing to piss the neighbors off or look like a pratt so is the above definitely ok ? and legal ?

im learning lol cheers all

[MikeFish]

1. their are two center silencers on this car, and i need to go to a garage, get these cut out and straight pipe work added ???? is that right ? and more to the point is it legal / m.o.t friendly ? are these what are known as resonators ?

There is a single box in the exhuast system that both pipes go into (the only place the branches come together). Although they both go into the same box there is no internal connection between the 2 branches (like a cross pipe conneciton) so cutting this box out and welding 2 straight pipes in its place will have no performance gain or loss. These boxes are silencers, also known as resonators. This is often referred to on this forum as the centre res delete. It only affects sound so no affect on MOT. Is it legal? It is illegal to modify your exhaust to make it louder in any way so yes it is illegal in the same way as most aftermarket exhausts are.

2.remove the vacum hoses ?? what the hell are they lol and just plugging them is that not a bit of a bodge job or totally ok ?? so what happen to the exhaust flap end where i remove the pipe from ? does this just get let unsealed ?
Your exhaust back boxes have a valve on them to control the noise. They are sprung to the open position and the car uses the engine vacuum to close the flaps. Even in Sport mode the flaps still close at certians revs / gears so disconnecting the vacuum hoses means they are open all the time giving the exhaust a better sound. You need to plug the hoses otherwise you will have a vacuum loss which will equate to a power loss. Easy to plug, just need a small screw and cable tie, the pressure is not great and unlikely to pop it out. The hose connection on the exhaust could do with a bit of tape of something similar to stop any crap getting in.

3. i have no idea what pre cat means, and if its going to cause issues with codes ect then maybe best i dont bother but will it still sound good ? i would like a nice roar but nothing to piss the neighbors off or look like a pratt so is the above definitely ok ? and legal ?
The exhaust system has a set of pre-cats and main cats. The pre cats are 400 cell and the main cats are 200 cell. If you buy Milltek sport cats they come in either 100 cell or 200 cell so the standard main cats are as free flowing as one of the milltek sport cat options i.e pretty good. However, the pre-cats are pretty restrictive. Their only purpose is to keep emissions low for the first minute or so when the main cats are cold and not very effective. This is required by Audi to pass emission tests but not part of the MOT requirement as they test the emmissions with the engine warm. So removing them is one of the best wasy to gain some power on the RS4. However, this could make the engine throw a fault so needs to be mapped out although some people have removed their pre cats and reported no issues. Removing will also increase noise slightly but the main reason would be for the power gain.
2 ways to remove them: either drill the cat out of the pipe which is a popular mod, or buy a sport cat like the milltek which has no pre-cat fitted but costs more.

[WRS4]

WOW, i owe you one lol, that all makes total sense and i get it now, you the man

ok so to be fair i think the car is fast enough for me as i have two kids as well (not that i drive like a pratt) but you know what i mean, so just after noise and looks really, so on that basis i guess i could leave touching the cats and do the other stuff for a better exhaust note ?

and can you confirm if this is LOUD, or just loud in a good way lol

thanks again for explaining all that

[S4WON]

Mikes old exhaust...

https://www.youtube.com/watch?v=YnmQhulLxSU

[MikeFish]

Ha ha, i love that video. Still makes me giggle watching that back.

[WRS4]

Mikes old exhaust...

https://www.youtube.com/watch?v=YnmQhulLxSU

so is that one of the exhausts he has purchased in the past or the original but doing what he has explained to do above?

love the sound, just possably a bit too loud but in fairness i may well try it

[WRS4]

its not that bloody loud in the car is it ????? lol

[MikeFish]

It was that loud in the car. But that is not the mod described above. That was a Tubi Rumore with Milltek non res centre sections.
Plenty of vids of the centre res delete on here.

[marc1]

I have some spare OEM back boxes and cats that were removed at 30k miles that would be ideal for gutting the pre cats and adding a non res centre to. I'm pretty sure the tail pipes are the same diameter as Milltek items too. Rather than the usual small OEM tails. PM me if you are interested, will save you having to butcher your existing stock exhaust and give you options.

[rickster147]

Mine is standard exhaust and recently took it to a custom exhaust place to have the centre resonator cut out and replaced with an xpipe this is anotger option if you don't want straight pipes putting in gives a more raspier sound
I've kept my valves working on the backboxes so I can chose between quiet mode and loud mode for when our lass and kids in the car
Been thinking of doing the pre cats but need to find a set with spacers first as I don't want any errors and dint want to remap the car just yet