You guys are right... Marketing claims of HP increases are usually baseless or over-inflated. I was even shocked when I had my completely stock Crossfire dyno'd at the track in 2004.

Even the manufacturer inflates the HP. I have since found that the MB W112 engine rated at 215 HP was done with an engine removed from the vehicle and put onto a test machine. Not a single part of the car was attached, nor were any of the accessory pumps, alternator etc. It was literally an engine on a platform attached to a dyno with advanced timing and none of the restrictive exhaust components. And this was done with the original W112 engine for the SLK320 in 1999...

So, our baseline of 215 is useless.

I go with the "50%" of any claim for aftermarket performance HP...