oem muffler hack

[j.fro]

The muffler has 5 chambers: Two outer, two intermediate, and one in the middle. The inlet pipe does go straight through the muffler. The incoming gases cause pressure, forcing themselves through the perforations into the intermediate chambers. I believe this action reduces much of the resonance in the exhaust. After the gases are in the intermediate chambers, they are forced into the outer chambers. From there they are piped to the center chamber, then out of the muffler. The Porsche Sport Exhaust uses external pipes to carry exhaust from the intermediate chambers to the exhaust outlets. By cutting into the intake pipe and allowing gases to flow directly into the outer chambers, you are creating an internal "Sport Exhaust". Modifying the exhaust in this way probably won't give you more flow, but it does produce a great sound, with only a bit of resonance.

If you want greater flow, the issue is first the header design, and then the bottleneck of the exhaust piping. The exhaust piping tapers down to 1.75" OD just after the headers.