Do these modifications really work? Do they really produce the numbers claimed and do you really feel a difference in acceleration and performance? Or is it all BS? Here all a couple of sites that claim that their kits develop an additional 30 to 40 horsepower. I also question the 3.8 and 3.9 litre kits, they claim 430 to 440 horsepower. How can a kit with a computer download, exhaust and sport filter make almost the same gains as a bore kit. Can someone enlighten me before I drop 10 to 25 g's.

http://www.ortonusa.com/porsche/996gt3engine.html

http://www.pes-tuning.com/

http://www.gmgracing.com/porsche_engine.shtml

http://www.cargraphic.com/index.php?...494,1640,1642/