headers/change of cats nessacary

if you get aftermarket headers (preferably ceramic coated ones, I suppose) should you get hi-performance cats or is it okay to use your stockers? also i'm not up to par with all the lingo, but the abbrv. ORY does that stand for your y-pipe? i'm not to sure... and what would be a mild cam setup that would give you some power with completely taking you A/C in the summer. i've heard that certain hi-performance cams has a negative effect on A/C system to a certain degree. thanks for the knowledge guys.

ORY means off-road y-pipe which have no catalytic converters. If you get hedders, you have to buy the y-pipe from the same company from which you got your hedders (weird spelling, I know, but that's how it's spelled) and you can either get a y-pipe with or without cats depending on your emission future.