The ads for the EVO engine state that they get 12000 rpm with an APC 12-6 prop. This sounds like a pretty strong engine if thats the case so thats what I put on the front. The first days flying I only got around 11,300 rpm which was dissapointing. The next time I took it out it started to pick up revs. After a few flights I was getting 11,600 rpm. By the end of the day I never checked the rpm but the plane was burning holes in the sky and I am really begining to like this engine! Based on this I would throw on an APC 12-6 and go have fun![