Wayne,
I believe the Imagine Auto supercharger will add approx. 80 hp :
http://www.imagineauto.com/boxster%20sc.htm
Real world results were completed on our in-house AWD Mustang Dyno. Base line results were apx 150RWHP increased to 230RWHP. That is a 38% gain by using your weekend to bolt on our supercharger kit.
Nick