Exhaust size?

An internal combustion engine is like a big air pump.. the faster you get it in.. the faster you get it out.. the faster you go..2 1/4 might be ok for a little 318,but your running a performance "340" it'll benefit from the larger pipes and those nice headers:-D:-D

As for some not noticing a difference between the 2 do you actually run your car all out(race it) or do you just putt around on the street??