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My 1991 Audi 90 20v - Back on the Road!

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  • #16
    Originally posted by steve briance View Post

    To a point but, as there isnt any real flow of fluid through the ABS solenoids there isnt much chance of any bubbles passing through and being free to leave when you get home and hook up the bleeding kit.

    The benefit of doing an DIY abs purge is that you can actually have your choice of bleeding kit hooked up while the motor and solenoids are operating. Flow = bubbles move.
    Ah yes, get it now.


    • #17
      ​​I've been getting tired of the resonance/droning from my custom exhaust.

      The droning is at 2 - 2.5k rpm and gets louder as engine load increases. Not good for passengers, either. It's wearing as it's at 40 - 60mph in top. I often drop down a gear or two to avoid it. Now I'm older, I appreciate a more relaxing drive so I'm on a quest to eliminate (or reduce) the drone. Often, I'd like to stay in 5th, in comfort. Outside of that rev band, it's actually rather nice. Quiet enough at high speed cruising (above 60mph) and sounds good when getting on it and working the engine through the higher revs.

      The car has the tubular, stainless exhaust manifold from factory.

      The custom system is a 20 year old 'Powerflow'.
      Cat was removed during the exhaust install. 2.5" (63.5mm) dia pipe used with 3 straight-through mufflers:

      - One small, round muffler where the cat was
      - One medium, oval muffler in the centre
      - One medium-large, oval back box with a single, oval tailpipe

      No dual pipe configuration - single pipe throughout, in and out of all mufflers. To be fair, it wasn't a lot of money, it's done about 100,000 miles and has never been an issue fit or build wise. That was done at a branch in Newport, when I were a lad ?
      Does anyone have any experience with adding a resonator? The original system would have been designed to deal with resonance. Either the cat was designed to help, or the small round box that follows. It's possible there was a chamber inside the huge oem centre box to address resonance.

      After a bit of reading and research, I've ordered a stainless steel 'Vibrant 1792 bottle resonator' to add where the cat used to be. At £50 delivered, I think it's worth trying. Lots of owners report positively that it addressed drone issues, either reducing or eliminating, but that's on all sorts of cars, engines and systems. A chap on Classic Audi Facebook uses a similar one with his 87 Audi Coupe GT. Think he has a cat though and his system may change depending on if the car is being tracked or driven on the road.

      I'll find out for myself when I get it installed (needs welding in) and will report back. Any thoughts or advice would be greatly appreciated.




      • #18
        Interested to hear what difference this makes for you. I need to get my system refreshed which is a 3" turbo back system and I get quite a drone when cruising along too.
        Greg Administrator & Webmaster

        '93 Coupe with a few tweeks


        • #19
          Hi Greg,

          Will report back once fitted
          Are you running a cat?




          • #20
            Received the exhaust resonator. Looks and feels very nicely made.

            Will hopefully get this installed soon. Here's a quick look video if anyone's interested...



            • #21
              I am/was in the same position as Greg. 3” turbo back. I had 8x4x12” centre box, 8x4x14” back box and 2x 21/2” tail pipes. Getting on in years I am now wanting something a bit quieter and after a recent 650 mile trip something had to be done. I have reduced to 21/2” just in front of the rear driveshaft and fitted a 8x5x18” back box with 2x 21/4” tail pipe’s. It’s not quiet but much quieter than before and much better at cruising speeds. The standard car used to have a Scorpion exhaust and I would say it sounds much the same as that, although that was a long time ago and the memory fades. I did look at a resonator but wanted to deal with volume as a priority. Be interested to hear the results as I may add one as well .


              • #22
                Yes, I'm determined to improve on this age old issue!

                I've emailed Vibrant asking for their advice before I go about installing it. I've heard their tech support is excellent. Speaking to the Powerflow chap, it all sounds a bit too trial and error for my liking, which I can't afford to do. Seeking some expert, scientific advice so I can be reasonably comfortable I'm trying the best solution. Lots of different configurations out there. Exhaust sound is so subjective, too.

                I supplied Vibrant a load of detail, my ideas and this video giving an overview of my current setup. Hopefully they can advise.

                Exhaust overview:

                Will keep you all informed!


                • #23
                  I've got a straight through system into a hollow scorpion centre box and baffled scorpion back box, got a peice of stainless pipe to remove the centre box as I think it's this bit that's giving me a bit of drone on long journeys. Also got no roof lining or interior pillar trims so you can imagine what that's like on long journeys love that I5 sound though when I give it a thrash.