Something extra engine
I use a good old OS 46FX engine (with its fourth set of sleeve and piston installed), with an APC 12.25x3.75 prop.
Members in my club cannot believe what I can do with this plane ( and I also sometimes don't believe it ).
If built light ( assuming you have the kit version ), this engine will be enough. But any of the other engines mentionned in the last post will be awesome too... But you might need to lenghten the landing gear a bit as prop clearance will be a problem.