I've got a 1978 M20J with the Firewall Forward "Horsepower Plus" STC SE2741NM. This is an IO-360-A3B6D with the stock dual magnetos and no other engine performance upgrades of note. I do have GAMI injectors which got me to a spread of 0.2GPH and reduces tendency to run rough, especially at altitude. This STC limits propellers to the stock McCauley so that's what I'm running. This engine has about 350 hours on it since overhaul by FF. No real issues with the engine so far. The airframe