I knocked out the 3 tubes in the GYT-R insert tonight. Took out the screw holding them in, heated the aluminum tip and knocked out the steel tubes. I caculated you get slightly more than double the diameter opening by doing this. Sound check: Not as bad as I thought. It sounds very similar when the tubes were in and alot quieter than no insert at all. I ran all 3 conditions while I was doing this. I like the sound it gave. Performance: Raining cats and dogs here, so no riding tonight. Will update as soon as I can give her a run.