I'm running a hand-me-down OS .40 FP (about 15 years old but with low hours) on my Tower 40 trainer swinging a 10 x 6 Master glass prop on 15% Cool fuel. The old .40 runs like a champ and starts every time but just doesn't seem to pull that well at full throttle. Take offs are a bit slow and touch and go climbs leave me wanting more out of the engine. Should I try a different prop or replace the engine? I've got my eye on a Magnum .46 as an alternate.