Really not any problems here in Texas with loud pipes (at least so far.) The general feeling is that the louder they are the safer the rider (from the people that can't seem to see a headlight on high beam) Also, so many places in Texas enjoy the revenue from bikers and don't mind a little noise with their dollars. However, Many cities in Colorado and a number of other states with national parks will only allow motorcycles and autos with stock pipes. This is the main reason I have chosen to keep the America stock.
