Venturi size gets talked about allot but what about the exhaust. Is there a formula for how many and how big to make holes in a tongue muffler? I've got an OS max S 15 side exhaust, the one made after the steel fin and before the FP, and I need to make a light weight muffler for it.

Should I calculate on the area of the exhaust port, copy it or reduce it? Not using muffler pressure but want to cut down the noise a little without loosing power.

Thanks,
MM