if you want speed, you want to stick with a .12 size motor, cars are lighter than monster trucks so they don't need the torque of a big block and benifit GREATLY from the 10000 rpms a .12 motor can turn over a big block, good .12 motors can make 2 hp or more which with the right gearing will get goin pretty fast at like half the weight(exageration but u get it) now as for the cars find out which handles best, not best top end, cuz i garente you'll be slapping mods into whatever you buy to go faster, and its no fun having a fast car if it can't be controled, trust me, my friend got a 4-tec3.3 and its the worst handling car i have ever driven, given it was stock and he doesn't know s about setting it up.