I am planning on retro fitting 6oz tanks as well, so with retracts bigger tanks, maybe the 40's will be ok. I am basically an OS man, with the occaisional K&B motor here and there. I may not stray away from my flavors. I agree that the .46 would be way too much, so maybe the comprimise would be 2 .40 LA's??? I would prefer a ball bearing motor in a twin engine I think.