I think you need to look to your suspension first to control weight transfer in a vehicle that is some way from 50/50 weight distribution.
I agree that rear pads of a similar friction coefficient are a good idea though, just not responsible for the sensation that Ricky123 was describing.
Too hard at the front and your front wheels will break traction, too soft and the front get's loaded too much and becomes unstable under hard braking.
The weight distribution of these cars is compounding the problem. On track mine is better with a full tank, it gets more lively as it empties but not to a level where it's a problem.