I'd say Marine Power has the 8.1 (496)motors dialed in pretty good now. I have 40 hours on a new 21 foot Ultra Stealth with no problems. This motor pures and is strong out of the hole. Pulls my 205 lb butt out of the water with zero hesitation unlike my old boat with a 454, that one had a tendancy to cavitate a bit. I was was hesitant at first because it's a new motor but so far I love it.