That is super not kool! A few years back, the caravan to Bimmerfest in Santa Barbara got a little out of hand, LOADS of people got pulled over and some very curious thing happened to me... I got a strange letter from the city of Santa Barbara asking me what kind of car I drove, why I was in the city and how often I go to the city. It was like "due to highway improvements we are conducting a survey..." I'm thinking they had my plate on radar and tracked me down. I never filled it out. I think the fuzz has always had it out for car events like these because of highway safety, which is fine but impounding a car is just a bit much. I wish you good luck with your situation.
No real mods... just loads of maintenance