ORIGINAL: RCKen

Gary,
The Ultra Sport is actually a plane that is a bit odd that it defies the normal ''more is better'' when it comes to engines. If you're talking about a 91 4-stroke the US actually is better with a 2-stroke engine in it. And if you're talking about a 91 2-stroke you would be better with the 75 AX. Trust me in that a US 60 with a 75 AX is one sweet combo!!!!! you won't regret it!!!

Ken