for the normal look... get some 18x7 or 18x7.5
if you're car is lowered with just springs, you won't be able to go any more agressive. springs tend to bounce and or sag after a certain period, and if your rims are too wide with a low offset, they may cause fender rubbing.
there's some dude who owns a GEN 4 CaM. and oh my goodness! he's running on 20x8 in the front and 20x10 in his rear. that's mad wide!!! he had custom body work. i never seen a Gen 4 CaM look so crazy. supposedly, it's gonna be ready for the next Hot Import Nights in Southern California. Be on the lookout, it's a grayish/silver/gunmetal color.