The components in the engine are already moving once started. It helps revs to lighten engine components, but since they're moving already, it's not as big a deal to get them moving faster.

Think of moving a round boulder. Getting it moving is the hard part. Once it's rolling, it's not as difficult to increase or maintain speed.

Tires and rotors have to initiate movement every time a car accelerates. It's the reason big rims aren't used on drag cars. Adding an extra inch to the rotor is adding a few pounds per wheel, rotors aren't light. I'd rather have them go on a diet instead, which is why I upgraded to 16" Torque Stars instead of some 17" or 18" aftermarkets. I'm focusing on speed.

Anyway, if you want big brakes, go for it. These are just limitations I place on my car (it's not an autocross). However, if you're going through the expense and trouble, why not just go with Fbody fodder and get the best? I may end up going that route if I can't do them on a stock rotor.