One of the "truths" of C/L stunt is that a side-mounted engine, cylinder to the outside of the circle, can't be made to run correctly for C/L stunt use. There is some basis for this belief, as certainly a Fox .35 with the tank mounted with its centerline on the same centerline as the engine will cough and spit and run rich on outside turns inverted flight.
The problem has been tank location, not the engine. For years, article after article said, "mount the centerline of the tank on the centerline of the engine", so everyone believed this to be correct. It is NOT!
The reasons why are too numerous and theoretical to get into, but the fact is that the Fox .35 and nearly all other side exhaust engines, will require the tank centerline to be about 5/16" higher than the engine centerline.
These Adjustable Tank Brackets, mounted to the sides of your fuel tank, will allow you to adjust your tank position until you get the same level flight speed in upright and inverted laps. Raise the tank (upright) if it runs richer in inverted flight, lower if it's leaner while inverted.