Torque Cars

A6 4.2 Quattro (C5) Avant Exhaust tips

Discussion in 'A6/S6/RS6' started by rmackinnon, 16 August 2010.

  1. rmackinnon

    rmackinnon Wrench Pro

    UK, Mansfield
    Audi A6 4.2 (1999)
    Hi All

    Had my 4.2 for a couple of years now. Just about to get all the essentials redone in a service (70k), and feel its time to spoil the old gal.

    I am planning to do a remap, but before i do that, i want her to sound more throaty and rumbly without taking away the joy of long distance driving which i adore the most in this car.

    I have Scottish in my blood so therefore reluctant to spend £1200 on an exhaust system, so like all tight arses, i am thinking about a DIY approach with a trusted garage.

    I understand there are considerations to take into account such as high flow cats, bore size, length of exhaust, manifold etc, but this can all cost for what is bugger all gain... but my questions are pretty focused to start with and hope someone can help me figure out the best solution.

    Because its V8, in essence the car has 2 systems running in parallel. They seem to join briefly at what i think is a resonator in the centre before parting to the rear corners.

    Firstly - do i need this resonator and what is its purpose beyond softening? are there different sizes and benefits to keeping/removing?

    Secondly - If i just do a cat-back system with stainless steel, remove the resonator and have a single back box each side? or would it be better to keep a centre resonator and remove the back box (or use a cherry bomb) all together?

    Thirdly - any benefit to getting the professional Thermo wrap around the exhaust? This I heard keeps the gasses hotter through the system increasing flow (and keeping engine bay cooler in crappy traffic)

    I am trying to achieve a descrete design so it doesn't look pimped (not even wanting to show rear pipes), just like to add some fruitiness and if possible not lose any bhp in the process

    Thoughts anyone?
  2. a6george

    a6george Wrench Pro

    England Sunderland
    6 speed 6n2
    the only thing I can sugest is, custom made is a lot cheaper than many think these days, plus they could answer all your questions and give you input to allow you to get the right pipes for you at the right price, give a few a ring to check out prices ect.
    good look and keep in touch as this is the route I will go down when the time comes to change mine.
  3. rmackinnon

    rmackinnon Wrench Pro

    UK, Mansfield
    Audi A6 4.2 (1999)
    i finally got it sorted after 3 weeks of going back to and from the garage for fine tuning.
    I got it done at a powerflow dealer.

    The trouble with Audi V8's is if you keep the pipes separate all the way to the rear corners, you will get an exhaust pulse between 2000-3000 rpm which sounds like a missfire, not a very pleasant sound. This is softened through the large silencers with original system so you wouldn't notice normally.

    So talking to Rabbit, he helped me find the solution. The key is balancing the system, this will even the firing sound and make the v8 sound more like it should.

    From the Cats you will need to merge to 2 pipes (2.25" - i think that's right) by welding together with a 4" (approx) long slit between them (to allow the gasses to pass to each side), then separate again to each corner. The 2 pipes look like an X where they converge.

    On each pipe after the X, i have a small resonator which then goes into a larger bore pipe (2.5") to rear silencers (to add low end depth), then our via 2 discrete exit pipes behind the bumper (so it still looks original).

    The sound now is awesome and sings when you drive, i cant help driving everywhere fast now, just to enjoy the sound! It is also still very comfortable cruising on motorway, which i do a lot.

    I was talking to someone who had an S4 with a Milltek (which have separate pipes from front to rear) and although it sounds lovely, it still has that pulse noise (just improved with a different design silencer on rear) + its over double the price.

    Personally, i now love the system i have installed, it cost all in all about £600 and im sure the engine does breathe a little better without any noticable BHP or Torque issues.

    Off to get remap tomorrow!

    If you want to see some photo's, send me a IM with your email, and i'll send them over.
Similar Threads - Quattro (C5) Avant
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