AJ,

You don't have problems with the tank draining out the vent in to the muffler when you are starting the engine? Or do you keep the plane on the wing tip until you start it? Or do you use a clamp or something on the lines?

I've been mounting my tanks behind the engine on my Skull Bandits, and I'm using Sullivan 6oz flex tanks with the vent line "sideways" so it's towards the top when the plane is level. My tanks are held on with zip-ties, and while I've had tanks knocked off in mid-airs and crashes, the sullivan flex tanks seem to give with the impact. I've not had to replace a tank yet. The zip ties fail before the tank or anything else does.