Plus a supercharged 330 is less to insure than a M3. As far as warranty issues, the dealer cannot void your warranty b/c you have a SC. They would have to prove the SC caused the problem in question. Some dealers will not want to work on your car , but there are some mod friendly dealers. I've never had any problems getting warranty work done yet. ASA kits are very reliable and are even used by big named BMW tuners/manufacturers like Alpina and Kelleners.