Well Gapple12 this is funny! I have exactly the same plane as you do and will put the same engine on the plane as you do (Great planes Extra 300s, and the SPE 40). So far I have an MDS2.18 in it, but the fuel consumptions is horrendous that is why I want to go gas. The MDS puts out about 21 lbs of static thrust with unlimited vertical but I would not mind an extra lb or so. So far I have about 20 lb with the SPE so I am trying to get some more out of it. Once I do I will put it on. Hey I have a question! How is the wing loading on the 300S with the SPE 40. Does the plane fly heavy or not?