What ratio fuel are you running? .75 oz ELF 2 cycle synthethic to 33.8 oz (1Liter) gas (45:1) 16 oz tank gives about 20min. flight times.I ran the first two 24oz tanks on 32:1 and for the flight I tried 40:1. I had opened up the stock exhaust to 1/2 hole but did not drill through the internal baffle. Not sure if that is a big cause of the lack of power.peek in that new hole you'll probably find just a few small holes, open the baffle with a few more holes. Also I don't have a velocity stack. Not sure how that affects it. I have read about replacing the carb to get the extra power. Wackerengines has them for $20. Just not sure if the engine will gain a big performance difference. I am going to buy one of their mufflers because my plane after the flight was spotted with dark exhaust residue. I am guessing I must be still running rich check the color and residue on your plug immediately after a flight light grey/tan is a good indicater because I though the point of going to gas was to have less cleanup too. The residue was harder to clean than glow. I have a couple of 15x6 props.Why not ? See how it flies. ! Do you think these are a better match or should I continue trying to get the 16x8 to work? Oh, and here is a big one. I have a escort wagon. How do you keep the smell of gas from getting all over the car?put a small plug in the vent line after you drain the tank and put the fuel in a flight box you can fit on your luggage rack.