Hi!
I have flown mine with a MVVS .91 twostroke and it flies fine doing big loops (100m diameter) and other manuvers. I use a 14x6 APC.
Mine is modified with pull-pull system (fishing wire) for elevater and side rudder and using a Tetta "Bubbleless" 500cc tank put next to the engine, under the cowl.
All servo gear is moved forward up to the firewall and original landing gear wheels are soldered instead of bolted together.
Aileron servos is Hs 225's instead of standard size servos.. and I 've mounted them inside the wing instead of outside as per plans, just for looks!
I've taken up lightening holes in the rear fin area, where the side rudder is mounted, to lighten the rear part of the plane.
With these modifications my GEE BEE weights exact 5kg.

Regards!
Jan K
Sweden