A guy I prep a car for is tired of his ears ringing after driving his track RX7. The car has a 12A street port, Weber 48, short primaries, basically a nice EP set up. He isn't racing the car so losing some power isn't a huge issue.

I'm looking for a quiet muffler to hang on the back of the car. 3" exhaust right now, the car has a dynomax bullet glass pack style muffler ahead of the rear end then a mazdacomp stainless out back.

At this point the car is parked and he is driving his supercharged Miata in events. We have a Miata parts car laying out back and he says, "Let's put the Miata engine in the RX7 so it will be quiet, I'm not driving it with the rotary anymore" I tried to tell him that's crazy talk, let me change the exhaust first.

 

RX7 1986-1992: Exhaust - Complete Systems: REV TII Presilencer - 87-91 RX-7 TURBO II -

ive had good luck with that. since its a 12A you might consider a 2.5" muffler too, in the rear it should flow enough, and 2.5" is much quieter

 

I Dont use anything else these days... Flowmaster Hushpower


Flowmaster 13016101 Flowmaster Hushpower Pro Series Mufflers


Do your research on them. The design behind them is solid. Best I have found...

 

I have a dual 2" long primary system that will fit the car. It used to collect into a three inch right around the rear end and go into the mazdacomp muffler. I'm going to try to get him to let me experiment with a couple different smaller dia pipe mufflers with the long primaries. I can pick up power with some bigger venturis, I think it had to have 40's for EP and I have some 42's in my collection.

For a brief moment last night I thought to myself, "I know, I'll put a turbo on it. That will quiet it down."

 

I'll see what muffler is on my car, because it's only producing 88db down the back straight at Road Atlanta....lol.

 

actually Peejay is running a power pulse on his car, and its expensive, but its not restrictive and he's on a bridge

 

Can't really go wrong with the powerpulse. My car is too damned quiet!



.

 

Yeah, it's very quiet, although at the last rallycross I was running the engine extremely lean, about 1000rpm past the point where the injectors go static (wouldn't rev any higher than that... hmm) and I burned out most of the gasket material at every flange, so it's gotten a bit louder.

Compare 2.5" exhaust with 24" long Thrush in the middle and Dynomax SS at the rear:

[youtube]fVYWleeCrfc[/youtube]

To same engine, with RB long primary exhaust:

[youtube]-rZAnwUd6kE[/youtube]

Power output did not change. Engine was a half bridge ported GSL-SE engine with a S4 intake. The new engine is much better on the intake side and has much more overlap involved. It likes the new exhaust just fine.

 

2 Borla XR1's, done.