No diff between cat and axle backs.
Corsa make a great product but +10 RWHP from mufflers only? That is (was till now) unheard off! Not true is my blunt statement. I think (they like most others) bolted it on a stock car, tuned it and then messured. You'll get the same gain (or very very close) with the stock mufflers still on from the tune only! I've seen 17 RWHP from a tune only!
I went on what I'd heard and seen and would have gone with a catted X and the rest stock for now if I known better...
I deffinately had a messurable TQ gain with the X and MACs, probably a few HPs too, and the sound, the sound, yeah the sound is awesome!! I currently have a bad droan at hard work; up hill, accelerating in high gear (SC uphill in 5th etc.), mostly just under 2000 RPM... They say that will get better when I get some miles on it and some 'insulation' (from usage) on the inside...??
KJ, poorer but happier
Fox Lake Racing
Power House 411
Sun Coast Creations