bolt on as much as you want. just leave in the MAF sensor and the O2 in the pipes. If you go cams to chage intake and exhaust you will need a special tune.I think if you cut the cats out the o2 will pick it up and the check engine light will come on. For intake and exhaust this is what i did and love it.I went with pypes x pipe(2.5) that cut the cats from 4 ta 2 and they are still carb legal. i also have super 40 flowmaster(2.5) left the rest 2.25. Cold air intake, 70mm tb, and trick flow plenum.