Roy,Before wrecking the silencer, I would be inclined to experiment on a plain extension pipe. The grass track sidecar guys put four slots in. They didn't remove the piece between the slots, they drove it inwards so it was visible from the end view. It won't make it much quieter but will take the"crack" out of it.
I think you are talking about a Decibel killer.
You can get them as units which insert into the tailpipe
1.4 KB Views: 5