Thanks guys. I will probably purchase a .55 AX that way if I want I can run it on the Twist for a while. Then maybe stick it on my 60in chipmunk and put the .46fx I have on the chipmunk on the Twist. I Kind of thought the AX would do good just making sure. The .46 fx pulls the 9 pound chipmunk around pretty darn good. Do the AX engines run as good as the FX series, realiability wise.