That is a nice kit indeed. I used it as a blueprint for the upgrades on my Boxster and now have all the parts except for the exhaust.
Let's put it this way... I don't doubt the claimed power figure given my personal experience
997.2 Carrera S in Carrara White. PASM-Sport Suspension (-20 mm), PSE.
987.1 Boxster S in Arctic Silver. OZ Racing Ultraleggera Wheels, H&R Monotube Coil-Over Suspension, H&R Anti-Roll Bars, Sachs Racing Clutch, Single-Mass Flywheel, IPD Plenum, GT3 Throttle Body, Recaro Pole Position Seats, PSE.