I’ve not done any back to back testing. I thought I had the latest cylinder, apparently not. For me, motor performs more than fine, thus not spending the huge money to change. When it comes time for my rebuild, if it approaches $2,000 for rebuild + cylinder head, I may consider another motor. As much as I like the Rotax the prices for parts are out of line. Have you priced a radiator or exhaust recently? Prices for those components for other engines are typicialy about 1/3.