Originally posted by usc
may be true for most aftermarket exhaust, but by personal account, i can say that my mpg went up due to the exhaust. it's the only engine-related mod i have on the car. my mpg went up ave 2.5mpg after installing my exhaust. i don't have any technical data to support this, only receipts from the fill-up 
:thumbup:
that's cool! never heard of that happening before, but more power to ya.