I have flowen both the OS46 and the OS55 on the Tiger 2 and to be honest you will be hard pressed to tell the difference in power...The 55 does have a tiny bit more but I sure did not find it to be a very big differance...What I did find was my 46 would always start by hand , was very easy on fuel , I always got comments on how quiet it was. It is very easy to tune but seldom needs tuning...