I just test flew my Seagull Ultimate 90 today. I only put an OS 91FX in mine with a pitts muffler. I was afraid that it would be underpowered, so I set all the control throws to the recommended settings. I was very surprised at how it flew. On the first flight it was stable as a rock, but the recommended control throws were just not enough. I had to use throttle to land it because I ran out of elevator. I adjusted the throws and the second flight was perfect. It landed very easy with no stall attendances.
A .90 2 Stroke is fine just for sport flying, but you would need at least a 1.20 four stroke to 3D it.
This airplane flyies as good as it looks