oh yeah.. you can also kiss your resale value bye bye :tsk:
yes when you cut off the spare tire, you have to reinforce the place to strengthen it up, and the weight of the exhaust should be the same as the spare, so i doubt it will mess up the performance.
so i guess if you replace the spare with the m3 exhaust, i guess it can be used as the "new" rear end protection in case of accident :dunno: