I put a Brisson 2.4 on mine. With an apc 20X10 I have near vertical and take off and hover at 1/4 throttle. It does a great inverted flat spin,wall and any thing else you want. A 20x8 or 21x8 should give unlimitrd vertical. Brisson said the engine will gain about 500 rpm as it breaks in. I only used about one ounce of lread in the tail and balanced in the middle of the CG. Only a little down elevator is needed for inverted flight.
I have a friend that has a DP extra. He flew my plane and said it flies as good or better than his DP.
I hope this has been some help.

Ron