humanvr4,

I think the Saito .91 would be fine in the 60 size. It is at the low end of the four stroke engine recommendations but with the proper prop it should be plenty of power. Unless you want to hover which the Twist doesn't do well from what I'm told. It should do some pretty good vertical climbs and most everything else you want to do anyway. Most 3D manuevers are not done full throttle anyway. I just started 3D and I had a Twist 60 for about a month before I hit the turf. I flew mine around almost at half throttle all the time. Now I have a Twist 150 with a Saito 1.50 in it and that is not the highest engine on the chart either. Now I'm just waiting for the field to dry up after our monsoon here in WI.

Good luck,

Gibbs