Racing Beat Collector/ streetable header

[vex]

I have a racing beat universal resonator to a dual magnaflow perforated stainless steel tube muffler (my entire exhaust except the turbo manifold is stainless). If you choose to go this route I would make the following suggestions: Instead of a y-pipe get a single inlet with dual outlet in the diameters you want. This will restrict a little bit of gas flow but it will be a huge reduction in noise. The baffles of the 'y-pipe' portion of the muffler will help cause destructive interference on the sound, mellowing the noise level. If you choose to forgo this suggestion you will need to find the 'sweet' spot on the rev range.

I have been pulled over exactly 1 time in my car for my exhaust, ever since then I have found the sweet spot to be around 2500rpm at partial throttle (it causes nearly 100% destructive interference on the exhaust noise--means it's almost silent. I'm being literal here).

If you still want less noise you can get a 'butt plug' which is a helical tube that causes the noise and gases to swirl around the tube as well as go through it. You can even further reduce the noise by filling the helical portion of the 'butt plug' with stainless steel wool. This will cause a greater reduction in the gas flow, but a significant reduction in noise.

[RETed]

If you're looking to maximize performance (i.e. flow) and minimize noise, go with anything that is a perforated core center tube with an offset inlet versus outlet.
This will give you the best of both worlds.
Walker Dynomax UltraFLO, Magnaflow, and Borla all makes mufflers like these.
Many are stainless steel which can handle the high heat of a rotary's exhaust.
Try and find mufflers that use "stainless steel wool" as packing, as this greatly extends life over fiberglass packing.
As a rule, bigger the muffler, the better the noise suppression.


-Ted