For anyone who thinks their muffler increases flow more than a straight pipe....

Why not put 3 or 4 in a row for combined gain?

The way to lower noise in a muffler is to reflect sound half a wave out of phase back on itself to cancel out. You want to do this with minimal change or loss of gas velocity.

The only time a muffler will make more power than a straight pipe is if the engine is tuned too lean with the straight pipe. Given a chance to tune both, the straight pipe will make more power every time.

John C.