why do i say this you ask, well after putting on the SLP cat back my car now feels a lot stonger. i went out to the track to see if it really made a difference and it did.

with flowmaster cat back
60 ft-------2.13
1/8---------9.72 @ 70.79
1/4---------15.22 @ 90.05


with SLP cat back
60ft------2.08
1/8-------9.50@72.42
1/4-------14.94@90.81

so if you want a cat back that does more then just make noise my vote is for SLP.