Maybe I might be able to add some insight to this. I will be taking delivery of a M3 CSL with a GTR type V8 engine (modified M5 dry sumped engine), putting out 455 hp at the wheels. Car is being further lightened with GTR carbon front hood, and rear trunk lid. Std CSL gearbox cannot cope, thus I will be using the M5 gearbox. Car has many other upgrades such as brakes, suspension etc. Will post pics and also impressions.