Phil,
I have a H9 Extra with a GT-80. It weighs 27 pounds empty.Your Sukhoi should be a couple of pounds lighter than that.The GT80 engine is an excellent engine for these planes but there is a thing or 2 you need to do.First of all,either junk or drill out the stock mufflers on the GT80 if you havent already done so.This will give you a big power boost.With aftermarket mufflers,mine will turn a Menz 24x10 at 7,040 rpm and a Fuchs 24x10 carbon fiber prop at 6,840.I could hover at about 5/8ths throttle. I swithced to a 26X8 APC which it turns at 6,840 and I can hover below half throttle.It also pulls from a hover with authority.But it should;that figures out to be over 60 pounds of thrust.It took about 5 gallons of fuel for the engine to start coming on really strong.The 26x8 also seems to help the plane maintain a more constant speed in level flight. I am truly pleased with this combination.Good luck! Rusty