My vote goes to 2 Chamber Flows/Mac Pro-Chamber mid-pipe. Of course Im somewhat biased, but it seems pretty widley acknowledged that this is a great sounding combo. I recently added two Magnaflow cats to my Pro-Chamber and was pleasently surprised by the results. The car is a lot easier to live with now (isnt un-godly loud inside the car, and the car doesnt smell like gas anymore.) The car still lets it all hang out at full throttle, and actually sounds better to me. It has a lower, more refined sound with the cats. Didnt really notice any power loss either. Actually picked up some low end due to the added backpressure vs. the un-catted exhaust. Car has an easier time breaking them loose, and seems to chirp second harder than it did before. I actually got a good chirp out of 3rd for the first time in a long time with this set-up.