I see in your sig it says " 3" inch full flows ". Are you running a full length 3" exhaust,or just the mufflers that are 3"? Anyway,I went to a 2.5" O/R h-pipe and 2.5" Flowmaster cat back on mine a few years ago,and let me tell you,there was a big difference in low end torque! With the stock 2.25" system,I had gobs of low-end torque,and when I bolted on the 2.5" system,I could really tell that I'd lost quite a bit on the low end side,but did gain some on the upper end. These guys are really trying to steer you in the right direction,so give their advise a chance. You never know,next time you might take out that Pontiac,instead of asking why you couldn't gain on him.