Sorry I missed your brake question.
I don't have any comparison figures but my C4 brakes are awesome. It stops in no time. The otherday I did a hard brake just for the fun of it at a stoplight and my woman slipped of the seat down on the floor
. She wasn't strapped up at that time. From 50 kmh to stop is just in a few meters!!
So I can for sure tell you that it is a BIG difference, just not how much bigger.
Jan