The SE5 has more than enough wing for the weight, not a problem , The cowl looks to be big enough to apply what ever muffler that may help with sound, AS for power , Half throttle should fly it just fine, don't have to use full throttle if you don't want to. The one I seen fly used a 120 rcv engine and it flew great. I don't know of any .90 size production made Gas engines, there may be some that converted a glow to gas. But IMO the G23 or the G26 will work great and be reliable and cheap to run.