You would probably be better off with the Irvine 53. I am wondering about the Y.S. because I can get a used one at a great price. I remember that on a plane I had years ago I was getting 14,000 rpm with a Y.S. 45 with a Mac's header and muffled tuned pipe on a 11-6 APC prop. A new Y.S. 45 costs about $160. and you don't get a muffler with them.