I have this same setup. I have a GP Extra 300S 1.60 Gene Soucy. My SPE 40cc is still going threw break in, but fly’s her around pretty well. I am lacking a little power in the hover, but don’t get me wrong, she will hover, but at about full throttle or a little less. For servos I use Futaba S3305 on all controls except throttle. I have had about 10 flights on her and no problems. I am not sure what plane you have, but this GP 300S was built long ago and not intended for 3D flying. I think she weighed in at about 14.5 pounds. Be patient with these engine, they get smother and much more powerful with time. Mine vibrated pretty bad for about the first gallon of gas, but came out great. Hope this helps.