Ok... my gen 3 'tec's stock y-pipe looks restrictive... the inlet from the manifolds to the cats is about 2" wide, but after the cats, it's only 1.5" or so... i was thinking about having a custom pipe made, with round, hi-flo cats that are 2" inlet and outlet. I have looked at a gen 4 'tec, and they have the wider pipe on both sides of the cats. Has anyone done this to their gen 3, and what were the results? I don't want to lose any bottom end by reducing too much backpressure. I mentioned to Alberto about removing the cats completely, and using MIL Eliminators in place of the rear O2 sensors, but he says it's not a good idea. I thought perhaps hi-flo cats and wider pipes would be good... at least better sound, maybe better performance? Anybody have any thoughts? Oh, and i am putting 2.5" stainless on from the cats back, with dual Magnaflow mufflers and tips, when they get here.