I have used this on a 2 stroke muffler with excellent results and see no reason it would not also work for a 4 stroke.

Use your Dremel and cut 2 grooves on the exhaust end (nipple, tip, what ever you would like to call it ). Put your extension on and when you secure the straps, make sure each strap is located over one of the grooves. It forces the deflector material into the groove and makes it more secure.