Irvine would without a doubt be my choice. I have a .53 on my trainer but its a .65 Size trainer so i guess a .53 on a .40 size trainer would be a little too much overpowered. My Trainer is a Graupner Trainer 65. According to the manual you should fit an .60 OS-FX or a .65 OS-LA. But thats WAY too much. The plane ways 2700Grams now, and my Irvine .53 with 12x6 Graupner 2-blade has 3200Grams of thrust. So its overpowered already With just too much engine you have the risk that your plane still fly's with your engine idle so that makes your landings quite hard

But my choice would be Irvine or MVVS