I recently installed a VF-Engineering supercharger on my 01 Z3 2.5 5-spped...the car is running great, but at idle after the car warms up (about 3 min.), there is a VERY loud rattling that occurs from the supercharger. I checked for loose things, vibration against things, etc. and the sound is definately coming from inside the supercharger. I called VF-Engineering and they said this is perfectly normal and that experimenting with different oil weights can help. Any opinions or suggestions?