83beast

out of those id say the flowmasters. theyre cheap and they sound good. as for the x- vs. h-pipe issue, either 5.0 Mustangs or Muscle Mustangs (cant remember) tested a crap load of pipes and the x-pipes had about 2-3 more HP up at higher rpm. not much difference.

5Liter Import Eater

i have the 50 series flowmaster cat-back, not as loud as the 40s but they sound good and real deep. there the loudest at about 2k rpm, higher then that its quieter. next im getting headers and x pipe which will make it a lot louder.

crazyhorse

they all sound good, but i like mac flow path .

bossmanGT

I just had the 40 series flowmaters installed today with 2.5 inch pipes and tips. I'm sold. I haven't turned the radio on yet.