Anyone know factualinfo on what the +s and -s are to exhausts exiting in front of rear wheels or out the rear. And is anyone really getting better gas mileage with their cat-back systems, air kits or programmers??????

 

hypertech max energy gave me about 3mpg more and a little boost on hp.i would say about 20hp.but the throttle is much,much more crisp.

k&n filter system-didnt see or feel any difference,except for the air sucking noise. it sounds like a 4 barrel at wide open throttle.

no exhaust yet.still trying to decide which one and how i want to run it.