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  • Need to build custom exhaust.......

    I will be upgrading the header on the car and was thinking about getting a Magnaflow for the center resonator and having dual 2.5" piping custom made from the header to the muffler.

    How do I keep the 2.5" through the muffler though?

    T

  • #2
    Don't you think dual 2.5 inch pipes all the way back is a bit overkill, I would think you would lose some serious back pressure.

    Comment


    • #3
      I wrestled with the same questions. When I was ready for an exhaust, I wanted to stay with a dual arrangement for purposes of ground clearance and to keep the appearance similar to stock.

      There are some problems though. Unless you are making an exhaust for a racing car, you NEED to have a really large muffler on these cars, or they end up very loud. None of the dual in/out mufflers that were available seemed like they would work. They were either way too small, or had the inlets and outlets separated by five or six inches. From a packaging point of view, it would not really work on an E30M3. I surveyed pretty much everything made by Borla, Magnaflow, and a few other companies. I could not find a combination of dual mufflers that I thought would work well, unless you are willing to go with a small muffler and thus a loud car.

      I wound up going with a single 3" for these reasons. I pretty much duplicated the setup Gustave Stroes used on his exhaust, same Magnaflow muffler and Borla resonator. This is, again, a LARGE muffler. Combined with the resonator muffler, the car is STILL fairly loud. Louder than stock, but tolerable. I don't think the parts are available to make a dual exhaust that is reasonably quiet.

      The other issue, is I went with a fairly high end shop (SPD in Sacramento) to build the thing. They are not cheap, and a dual exhaust would have cost a lot more in terms of labor and materials involved. I also wanted a "modular" exhaust in the sense that I could remove the resonator and replace it with a cat or straight pipe with "V" band clamps. If you think about it, fabricating and packaging this sort of setup with a dual exhaust would be very complicated.

      The only real down side to the single exhaust is that you need to start it with a quality "Y" pipe. SPD and Burns can build top notch "Y" pipes. Not cheap, but I am sure no more expensive than a quality "X" pipe you would need for your dual system anyway.

      As it turned out, SPD packaged the exhaust in such a way that I really don't think I lost any ground clearance from the stock system. It is very neatly tucked in, and they ovalized the tube where it passes under the rear subframe.

      HTH
      Last edited by Ironhead; 04-24-2004, 11:59 AM.

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      • #4
        I plan on keeping the SS muffler I have (if it will mate up), PLUS the Magnaflow for a resonator.

        Maybe I should just buy the 50/50 SS center section and the 50/50 header?

        What is the best way to get something mated to the 50/55 header?

        Tony

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        • #5
          Mating to the 50/55 header is what drove me to get a custom exhaust in the first place. There isn't any other good way I know of, other than just buying the Sport EVO exhaust. I actually considered that, but it costs around $1800 and there was some doubt that it used the same hanger arrangement from the subframe as the stock one does.

          You "can" enlarge the bolt holes slightly and bolt pretty much any system to the 55 mm header, but there will be a large "step down" in tube size that can't be good for flow.

          I assumed you were planning a new rear muffler, because the Supersprint would have way less than 2.5 inch pipes. I don't think there would be any point in building a 2.5 system then running it through the Supersprint.....

          This is a dilemna. If I was doing it over again I might have used a different header. Then you have more exhaust options.

          Comment


          • #6
            Originally posted by Ironhead
            Mating to the 50/55 header is what drove me to get a custom exhaust in the first place. There isn't any other good way I know of, other than just buying the Sport EVO exhaust. I actually considered that, but it costs around $1800 and there was some doubt that it used the same hanger arrangement from the subframe as the stock one does.

            You "can" enlarge the bolt holes slightly and bolt pretty much any system to the 55 mm header, but there will be a large "step down" in tube size that can't be good for flow.

            I assumed you were planning a new rear muffler, because the Supersprint would have way less than 2.5 inch pipes. I don't think there would be any point in building a 2.5 system then running it through the Supersprint.....

            This is a dilemna. If I was doing it over again I might have used a different header. Then you have more exhaust options.

            So the 50/50 header would be better huh?

            T

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            • #7
              go with the 50/50 system....header and then SS center and muffler...

              Just my opinion

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              • #8
                So the 50/50 header would be better huh?
                I don't know if it's "better", but it would definitely be easier and simpler.

                To know which is better in terms of flow, torque, and HP would take a lot of dyno testing, etc. Don't know anyone who has done it.
                Last edited by Ironhead; 04-24-2004, 04:01 PM.

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                • #9
                  What about the System John has on his car?

                  Super Sprint also makes a 60mm Stainless system with or with out cats.

                  If I even get the CC down and get some cash I'm going to have John send me a system with some nice cams.

                  Do not click
                  At least it's German

                  Comment


                  • #10
                    on my car my exaust guy went from the cats back with dual 2in pipes to a dynomax welded race muffler that is 3in in and out making the muffler the collector. noise is low and tastefull and this is on a 3.0 s50. if i didnt have cats we would have run 3in back but with the cats in place you might as well run the same size as them. hes made a few s14 systems that he used 3in back with out the cats and said it flowed and sounded nice

                    Shes sold now :(

                    Comment


                    • #11
                      Tony,

                      I have stock headers (boo) but why not do what Gustave did? (Ironhead mentions this) 3" piping? This is what I have done on the Alpineweiss and on the Henna 2.5 (also stock headers) but on the whitey, 3" piping to XR1 oval Borla Muffler to XR1 round Borla muffer and on the Henna, straight pipes to Borla muffler XR1. All ofcourse using Y-pipes.


                      Comment


                      • #12
                        Originally posted by Bavarian3
                        Tony,

                        I have stock headers (boo) but why not do what Gustave did? (Ironhead mentions this) 3" piping? This is what I have done on the Alpineweiss and on the Henna 2.5 (also stock headers) but on the whitey, 3" piping to XR1 oval Borla Muffler to XR1 round Borla muffer and on the Henna, straight pipes to Borla muffler XR1. All ofcourse using Y-pipes.

                        How loud is that?

                        Comment


                        • #13
                          I have 63 mm OD (2.5 ") (or 60 mm ID) dual pipes
                          all the way thru the muffler, the muffler tips
                          are 76 mm each. Orignally, the system had
                          2 metal (200 cell) cats and a rear muffler
                          (that was rather empty). It was extremely
                          loud on my engine (loudness is also
                          very much engine dependent). You could not
                          hear the airbox with this exhaust system.

                          So we went back to the drawing board and
                          reopened the rear muffler, wrapped the straigh
                          thru pipes in ceramic weave mats and then filled
                          it to the max with wool. That quieted it down
                          quite a bit, but it was still simply too loud.
                          Back to the drawing board again...and had
                          2 center mufflers (1 per pipe) made that sit
                          right behind the cats. They are also of the
                          stright thru design. Now the noise level
                          is much more tolerable with no bad resonances.
                          It is still louder than stock however.
                          It gives a nice aggressive sound, but without the
                          droning noises and I can hear the airbox once
                          again.

                          John

                          Comment


                          • #14
                            Originally posted by John
                            I have 63 mm OD (2.5 ") (or 60 mm ID) dual pipes
                            all the way thru the muffler, the muffler tips
                            are 76 mm each. Orignally, the system had
                            2 metal (200 cell) cats and a rear muffler
                            (that was rather empty). It was extremely
                            loud on my engine (loudness is also
                            very much engine dependent). You could not
                            hear the airbox with this exhaust system.

                            So we went back to the drawing board and
                            reopened the rear muffler, wrapped the straigh
                            thru pipes in ceramic weave mats and then filled
                            it to the max with wool. That quieted it down
                            quite a bit, but it was still simply too loud.
                            Back to the drawing board again...and had
                            2 center mufflers (1 per pipe) made that sit
                            right behind the cats. They are also of the
                            stright thru design. Now the noise level
                            is much more tolerable with no bad resonances.
                            It is still louder than stock however.
                            It gives a nice aggressive sound, but without the
                            droning noises and I can hear the airbox once
                            again.

                            John
                            This is what I was talking about doing earlier. Getting the 50/55 header. Then getting the SS 60mm race center section and adding Magnaflow resonators in the center section. Then either keeping the SS muffler and adding larger inputs, or just getting another Magnaflow with dual in and outs for the final backbox.

                            T

                            Comment


                            • #15
                              Whatever you do, make sure the stuff can take the heat. With a cat / closed loop, downstream has an easier life. But with no cat even the rear muffler can get "heat stroke".

                              Stan

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