Sailor,

Mine bolted into a threaded hole on the back of the engine. Did not have to do any modifiying. Make sure everything fits well or these mufflers are known to crack. Mine came with two washers to use at the connection to the muffler, but no instructins where they go. Emails to JA went unanswered. I just used them and the bracket and made sure there was no induced tension or stress on the muffler.

Mark