finally got to the dealer and it was a bad motor in the exhaust, thanks for all your help. they just replaced it and so far so good
guess this definitively answers my question as to whether or not a full exhaust (Quat D ex box) for the M1100, which eliminates the exhaust valves, would cause a check engine light. thanks for the input guys.My check engine light came on at around 1630 miles. It turned off and re-appeared at 1800 miles. The error code was EXVL (exhaust valve motor). I'll be bringing it to the dealership soon.