First off, Phat, if you're just starting this, don't go and get a Rossi based motor or anything. I saw on another thread you were asking about what seems to be your first car.
My advice (and again, take it or leave it. . .
) is get a good solid motor with decent power - I first bought an OS 12 CV - about .7 hp and rock solid - it still runs great. Once I learned to handle that I went and got a higher power motor. I now run a Mugen MT12 and love that baby!
When I was running the OS, I laughed at the guys running RB Concepts, Mugens, Rossi's as I passed them on the sweeper that they MISSED. . .and crashed into the wall. . .
But, if you really want a lot of power, any Rossi based motor is going to have 'loads of power - Mugen, RB, NovaRossi - all will have more than plenty of power.