I have just ordered the world models extra 300s. What engine should I use? I want to tear holes in the sky and pull out of hover with authority. 2stroke,4stroke,gas I dont care.

Crash90 I assume you are talking about the 80" extra300s. If so I would say YS140dz /Saito 1.80 for a 4 stroke or O.S 1.60fx or Moki 1.8 / 2.1 for the 2 cycles. I have never looked at one up close to examine it's construction quality but from what I hear you should be ok with a 42cc Gas engine on it. I would go for the DA50 if I was going the gas route.

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