[flair666369]

Hello all, I have a 98 GMC Z-71 5.7L, K&N intake, MSD Ignition + 8.5 wires, Hypertech low temp thermo, Superchips programmer, dual remote oil filters, and full synthetic fluids. Recently the crankshaft broke, so the engine is being rebuilt with a Comp Cam custom grind for the elevation here in colorado springs, and flat top pistons. In addtion they are also installing the Doug Thorley's Tri-Y headers that I bought right before it blew. I've tried researching everywhere but I cannot decide how to finish the exhaust system. My plan is the headers down to dual cats, to a Magnaflow x-pipe (I already bought) to single?/dual? muffler(s), all to running 2.5 inch pipses until the exhaust tips. To me sound is a byproduct of performance, and I have to keep it emmisions legal. It is hard to find info on which companies put out the best hp gains and reliability, especially for cats. I'm in the army and I want to do this right the first time, it's hard to buy experimental parts on a government paycheck. Any help is greatly appreciated.