In reality there kit proberly has a blow off valve so you would get less than 0.5% Boost becuase trust me here the compression on a standard 8V is too high and conrods will smash through that little ol head of yours! don't expect that stock engine to last if you boost it!
Weight to power always has alot to do with handing and the way a car feels.
I would prefer handling over all out power which you loose anyways through smoke and tyres!