[Kevan]

Motors are much of a muchness, you won't really feel torque differences in motors until you have tyres that give great grip.  The #1 most important thing on a car is tyres, that's where the lap times are when you're racing non-mag.

So in order of most important (non-mag):
1. tyres
2. gearing
3. motor

Of course chassis ballast down low helps tremendously with full interiors.