Hello Dave,Well I have the fist batch and I drove me nut for years on end,became a very good glaider pilot. As my last hope on that engine, purchase a cline regulator and it havent gone dead stick and the lousy midrange is gone. So happy with the 2300 that bought another one. Is on a 72 inch sukhoi w/ a17/8 and it haul it around with a lot of authority. Also own a REVPRO with a os 1.60,hatori header and pipe cline regulator 18/10 apc. Imo the st has more guts than the os. Later