Yeah, interestingly the major German tuners (G-Power, AC Schnitzer, PP-Performance, Hamann) claim that gains from tune-only on stock M3 are approximately 20-30 PS to the crank depending on the company (Euro calculated HP), corroborating to US tuning companies' observed 15-20 whp or 17-25 hp crank (US Calc HP) when normalizing for drivetrain losses. Doesn't seem like there are any outliers from any part of the world!
Originally Posted by alpine335i
All the tunes are pretty much the same, go with which ever is easiest for you. The fanboys/haters will post shortly and tell you what you should get if you can't decide.