Of course the first choice wud b ys63 being pumped etc also the saito100 is sure the other combo if u pref a simple no noncence fourstroker . if ur the 2stroker kinda guy then a os50 or 61 fx will also suit . better avoid heavier motors that weigh more than the above. and i feel that there is an error in the weights comparision fs70 is 580 gms and the os90 is 680 gms. i have one ucd with the ys63 and the 6v nicad is way back near the servos . so anything heavier up front is a bit iffy.