personaly, if it was me and i was putting all that money into beefing up the engine, i would definatly do some tuning to the transmission, kinda like if you put a 700 horse V8 bolted to a 2 speed powerglide tranny, with a stock driveshaft, somethings going to break, and i bet a million dollars i know what its going to be
of course, thats just me, i know nothing about the tranny in a stock cavalier, i might be wasting money doing that, or i might be saving time and money, you never know