IF it's the Carl Goldberg model, then the extra weight may or may not be needed. I recently put together the ARF, and I modified it for dual rear elevator servos. Even with this mod, I came out pretty balanced with a magnum 120 glow engine (app. 3 lb engine). This was with the battery all the way to the firewall. I almost added too much tail weight with the servos, but all worked out ok. The CG is at the back of the recommended range, but I want it aerobatic anyway.

Then again, this plane has such a large balance range, that I suppose it could handle a small gasser. I'd check out Scott Ellingson's conversions before i bought anything. 163 bucks shipped for a 25 CC gasser--which would go perfect in this plane--and that includes muffler, carb, and all. Engine weighs 3 lbs 7 oz RTF. Not a bad deal.