fullmann

so, i've searched and found that the normally aspirated 3.4 v6 seems to like a 2 1/4" exhaust, and the supercharged engines like a 2.5" exhaust.

is there going to be a drawback to putting on a 2.5" exhaust in prep for a supercharger that has yet to be purchased (and may or may not really make an appearance), or will my power and mileage suffer?

I also wanted to find out if there is any problem with ditching the dual cat setup and going with a single high effeciency unit? my truck is a california emmission spec (although not in california??) and I realize that it will probably set a check engine light, but that will be remedied by the urd o2 signal piece.

any other input for a header/cat/exhaust combo would be greatly appreciated, as my cat is on its way out and I figure nows the time to do the whole system, rather than pieces that may or may not work together.

ETA: the rig is a 00 4runner sport, 4X4, 5-speed, 95k miles.