the older extreme's only pulled 350rwhp.
Im with marcus, except im not a fan of KB's anymore since i've had 2 friends go through 5 blowers in a matter combined total of 4000 miles. ALl of them were the so called "fixed" ones that took care of the oil leaking issue.
Stock saleen with 4.10's, Vortech or Paxton at 8psi, 42's, Lightning MAF, cobra tanke and pumps....probably net you the same hp as a KB, but from what i've seen, far more reliable.
Im not taking anything from KB, just my personal friends experiences with them have been nothing short of awful, while my vortech experience was nothing short of greatness. THe KB will make a better street car, but at the same time, a street car has to be reliable.
I do totally agree with a non s/c car and adding what you want, just pick what blower you want wisely, and research the heck out of everyone before you purchase.