I run a Menz 26-10 on mine. I've seen 6400 on a good day with this engine prop set-up. Standard Johnson in cowl mufflers. This is one of the best running gas engines I've owned. Its very smooth and ultra reliable. I'm the 3rd owner of this engine and I have owned it for 6 years. Mines the TOC version...This motor is really quiet considering the mufflers that I have, the added weight of cannister mufflers with the weight of this engine may add up to something undesireable. I think 24-24.5lbs is about max for good performance with this engine. I'm flying an Aeroworks kit built 31% Extra 300L with this motor, 24.2lbs. Just my thoughts on this...Walt