Wagner the Saito .72 will turn a 13/6 APC @ 9,800 in flight tune all day long. The .61 2-cycle will turn a 11/7
about 11,500. The Saito has better throttle response, burns less fuel, and is is lighter. There is no comparison
for fun fly and 3-D type flying. As far as to big an engine I have. I once broke in a SuperTigre .90 were a .60
hsd been. I thought what the hay the bolt pattern and length and weight are the same why not. it did not crash the plane but the negatives outwieghed the positives. The only real plus was the verticle. The drawbacks were
torque off center whenever the throttle was slammed,and the longer prop getting in the grass. In normal flight it really wasn't much faster. Remember it takes ten times the horsepower to double airspeed. It worked to break in the engine, but flew much better when the .60 was back in place. It sounds like you want someone to tell you it's OK to put a .90 on that SIG. Truth is it will fly but all around performance will suck. Narrow you choice to
the .61 fx or the Saito .72 and you will be happy. Both of these will make that .46LA look bad.
later daveo