Im posting this for a friend, and im not sure what his problem is

He has a lt1 -camaro he added a msd ignition box and coil. and now when he gets on it it pops and back fires. He got walked by a mustang and id like to get him runnin good again.

Any ideas how these changes would have made the car run like crap now?

 

First thing to do is swap back to the original coil. If the problem continues they you know there is a problem in the MSD box or its wiring. If it stops then you have a defective coil.