You'll have to check your plug tips (assuming you don't own a dyno and a sniffer) and see if they turn pale brown or white indicating a too lean Air/Fuel mix. Too lean and your air cooled motor runs too hot and, yes, things get burnt. Clean your plugs thoroughly, have a moderate run and take a look. You may also find that without the baffle breaking up the "rebound" pulse (wave) in the pipe that you've lost some bottom end torque. A lightly packed baffle can cure that and maintain that crazy loud pipe that you desire.
