We need a little more info here. What prop are you using and what is the weight of the plane? A slightly aft CG will help with tail feather authority but be careful with this. I would use a 15x4 APC prop on that engine if I was trying to hover it and your model should be between 7-8 pounds max. preferably lighter. I looked on Tower and saw a few GP Extra 300s options. If you have the 40 size ARF you are definately light enough but will be way to nose heavy with that Saito. If you have the 60 size kit you are right there on weight and might just be prop selection and a small CG adjustment. Your question however might be better answered on the 3D forum although I know they are much slower to respond. Again I will urge caution if you decide to adjust your CG.