Well I can't say for sure about this formula but I have a 2.5" catback exhaust w/ a 55mm bored tb and now a ported intake manifold. I used to put a silencer in my exhaust. Once I forgot to bolt it in and I revved the engine ... basically it shot from the car being right in front of the garage (my garage is located behind my house facing the street) all the down the driveway, across the street and hit the curb on the opposite site of the street and clanged there and landed in the people's across the street lawn. hehe.

The exhaust gases at my exhaust tip has a mean bit a force behind it and it's DAMN hot. It sweet.

-"Easy Mac"
05 Mazda RX-8 (RR8 #88)
99 Eclipse RS 398whp & 372lb-ft