The next performance upgrade I purchased was the UUC Rasp X system in September of 2003. I bought this to get rid of the raspy metallic noise that the E46 M3 seemed to make at higher RPMs. This was the first generation of this system and it does remove the metallic rasp. The one drawback to the system is it does not add any power and but does add weight. So the removal of the rasp sound negates any real performance in retrospect but at the time it was the hottest thing on the block.