I'd like to throw in two cents, your talking about cams when you should be talking turbos. I think cams are more for adavanced racers. After you start from the bottom up.
A stock 420A with cold air and exhaust only make it more effecient. If your looking for power start with the turbo mani, turbo, fmu, and downpipe, intercooler, pipes, blowoffvalve, High pressure fuel pump, Lmfao, yeah theres alot to cover and a cold beer.
Do a little reading, theres a ton of info here