My club has a 96 db @ 3 metre noise limit measured from the side opposite the exhaust. We tested a Wren 44 in a Fivejet at the side opposite the exhaust, the front. The results were not encouraging, the limit being exceeded at about 3/4 throttle. BUT - a prop driven model's noise increases greatly once it's in the air & the RPM speeds up. Of course a turbine's RPM is limited by the ECU so it does not speed up & make more noise in flight. That's the excuse we use. [sm=idea.gif]- John.