Sport Pilot, good suggestion- then again I'd want to compete with the OS91FX from the stand point of price,power and reliability. Years back I ordered a Cajun Prod's. TigertailIV and found at the time 1999,that It was next to impossible to get a rear exhaust 10cc so I settled on the 91 which seems to equate to the same power as a screaming 10ccwith pipe and with out all the associated problems noise one of them. Just my 2 cents.