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anyone with a quiet non stock urs4 exhaust?

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  • anyone with a quiet non stock urs4 exhaust?

    Right I have a urs4 advant that's just a bit too loud. It's 400+ HP so the stock exhaust was becoming a bottleneck and has been replaced. I had a 3 inch down pipe with no cats feeding into the stock system. The car was quiet, but I felt power was restricted. I fitted a home modified aftermatket stainless bi turbo s4 mid and back section which is a twin 2.5 inch system with 2 boxes. I even added a central resonator, but still its loud. The car does pull harder and I no I could advance the timing a little now and egt is lower.

    The car is only loud from about 2.5 to 3 k rpm. Other rpms are nice and quiet, but I can't stick the drone on the motorway. So if you have a quiet system for road use can you please describe it. I'm prepared to mod my system or even make custom boxes, but I want some feedback of peoples experiance. Cheers des.

  • #2
    My 3" turbo back system with race cat and two boxes is similar. It sounds great but has a bit of a drone at 3k rpm which can get a bit tedious when at cruising speeds! Above and below 3k seem to be fine. It was suggested to me that this could be helped by extending the tailpipes slightly so that they stick out futher past the rear bumper. I have not tried this but it maybe worth a try as it's a relatively easy mod. What did help mine was using sound deadening matting all over the boot floor and spare wheel well. This made a significant difference and made the drone much more tolerable.
    '93 S4 Avant now back on the road complete with new shiny go faster bits.

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    • #3
      My spare wheel well is full of lpg gas tank so the mass of that should help, but still the constant brrrrrr at 2.75k is cracking me up on long steady drives. I have already cut open my new stainless backbox for a look and its 2 perferated tubes from one end to the other. The casing is, or was packed with fiberglass type matting. I have made the lid of the box removeable, and have tried a few things eg restricting one of the pipes which helped lots, but I don't want to hurt flow. So I reckon I could build a back box with almost 3 times the internal volume. But would this be worthwhile? Cheers des

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      • #4
        My urs4 had a 3inch turbo back exhaust when I bought it from AndyP in 2008, recently changed part of the system to 2.5inch from cat back and the sound is a lot nicer and fairly quiet and only really loud when I want it to be. Much more enjoyable to drive, a lot easier to hear music when in the cabin.

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        • #5
          Yep shrinking the tubing size helps kill the boom, but also restricts power. There must be a compromise somehow..

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          • #6
            3" downpipe, 3" electronic bypass, straight thru 3" centre box into stock backbox.

            Basically stock twin back box is equivalent to 2.75" system and being at the end of the chain it offers no restriction to the engine as the gasses have cooled down by that point and take up less volume.

            The car is complete bliss to drive frighteningly silent to the extend you hear a light whistle of the turbo whilst cruising, with a bit of a rasp on WOT. Get to a trackday and adjust the bypass valve for desired sound and flow .

            As a test I've done prolonged full throttle passes with the valve shut and open and there is no difference in EGT's so the stock back box offers no flow restriction compared to a 3" downpipe straight to atmosphere.

            Haven't got any pics bit I think Andy (Ross's brother videod the underside at the MRC rolling road day).
            UrS6 Stroker + HTA3586 =

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            • #7
              I have this 3" RAY-cat back stainless exhaust with a custom 3,5" DP and a straight 3" middle part without cats. The sound is quite low but there is some drone at 2-3krpm, but not too bad after all.

              http://doc-power.com/index.php?page=products&group=12




              If you want full stock quietness without any performance loss you can always use the stock exhaust and put a exhaust cut off valve to it like this.

              Last edited by Thuppu; 16th July 2011, 11:58.

              Audi UrS4 Avant 2.5 20vt - twincharged - Project
              Audi 80q B4 Sedan 2.2 20vt - Daily user
              BMW 320d Touring e91 M-Sport - Daily user
              BMW 740iA e38 - Project

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              • #8
                Interesting. Jb is your center box around the gearbox or further back. Hunting for pics of it. I wonder if I could fit my stock back box on the mid part.

                Just how loud is the car with the bypass open?

                Cheers des

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                • #9
                  I got a straight pipe from downpipe to just b4 the diff where the centre box is and then straight into the backbox. As for the bypass when fully open its jokes just ask macandmar. Although it takes 4 secs to fully open so there is various levels you can set it to.
                  UrS6 Stroker + HTA3586 =

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                  • #10
                    Right, I have a few things to try then. Will let you know how I get on with it. Cheers lads

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                    • #11
                      A update then. As my stock back box was tired looking so I went for a sebring one in eBay which is normally 160 quid. I got mine for 60 for some reason. It's stainless and painted black so looks more stock other than the bigger bad boy tail pipes. This sebring box is tuv approved so I guessed and hoped it would be quiet

                      Last night I took off the modified bi turbo back box and fitted the sebring by hacking my central section. The central section has been hacked lots now so I might redo it in the future. My system now has a 3 inch resonateor near the gearbox which does nothing for sound other that catch speed ramps, then an adapter into 2 2.5 inch pipes feeding a aftermarket rs4 biturbo mid box arround the rear diff, then adapters down to 2 x 2.25 feeding the sebring.

                      The results ate good. Almost no boom, and a nice roar on boost. It's not as quiet as stock, but it seems great at cruse. As I say I would like to bin the resonator and mid box which are both small in size and replace them with one bigger mid box which would tidy up the plumbing.

                      But thanks for the advice rwd19t. Stock backboxs are the way forward..

                      .

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                      • #12
                        Pic of the rs4 back box removed compared to the sebring in black that I fitted.

                        Sent from my Desire HD using Tapatalk
                        Attached Files

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                        • #13
                          Originally posted by RWD19T View Post

                          The car is complete bliss to drive frighteningly silent to the extend you hear a light whistle of the turbo whilst cruising

                          Same here, and
                          05 Allroad
                          05 Seat Alhambra

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                          • #14
                            I was very impressed with JP's setup, with the bypass closed its very quite and refined, less intrusive than an S2 with a milltek system. With the bypass open its just frickin hillarious, makes all kinds of noises on full chat
                            91CQ20v - Gone to a new home
                            93UR-S4 - The Magic Carpet
                            94S2Bus - The Emerald Express

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                            • #15
                              Originally posted by mcandmar View Post
                              I was very impressed with JP's setup, with the bypass closed its very quite and refined, less intrusive than an S2 with a milltek system. With the bypass open its just frickin hillarious, makes all kinds of noises on full chat
                              sorry to resurrect such an old thread but is the valved pipe before the cat or after the cat before the back box? Whats the best way to go? thanks
                              - 1995 BLACK S2 ABY

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