When I was in High School, Yes way back then, I drilled out an old Yamaha 6A4a with a power drill just to see what happened. A lot happened, but none of it any good.
While I should have never had this mouthpiece in the first place, the tone it had was ruined and the slots got really funny. Granted I really drilled I out, I would not recommend anyone do this to one their own. Find a trumpet repair guy to do it.
Just for fun we also ground down a rim to make it totally flat, made a triple cup mouthpiece, and added a ton of solder to a mouthpiece. Some interested results, but I am sure you can see I am not a repairman or a designer, that should tell you something
