Hi, Im in Riverside county. I take my car in to Riverside BMW which is Great in my opinion, and theres no issues with my exhaust. The key to any dealer attempting to Void your warranty for exhaust mod would be for them to prove the mod is the direct cause for the failure. Your car is still under the OEM warranty. Your New Exhaust is not.
FAST ISN'T FAST,SMOOTH IS FAST!!!!!!!!!!!!