2 1/2 inch exhaust on a 318...

I think of it this way. Pump gas is already $3 a gallon here (yes that 87oct) so why not go for broke (literally) and run high compression and some race gas.

on the street you probably wont feel the differance from 2.5" to 3" but your gonna hear it. Also Im willing to bet a a 2.5" system with an X pipe and some straight threw muffs will out flow my 3" pipes with no cross over and chambered Flowmaster.