My fuel tank is ~ 3 inches back from the stock location. It's back as far as it will go without me needing to cut into the fuse. I am using a Cline regulator with the engine inverted. I am very pleased with this setup. The engine now operates flawlessly. Consistant even power from beginning to end of run. I chose the cline over the perry specifially for that reason. With the cline there is no adjusting to do and there is no fuel entering the engine until the prop spins. It is so simple to use. I fill the tank, hit it with an electric starter and wham! She fires up instantly. No priming, choking, or messing around.There is no adjusts with the cline other than the standard needle adjustments. I'm very pleased.