The world's most powerful potato cannon

Just a quick overview of how my cannon works. It is made entirely of PVC. It is a "hybrid" design meaning that it uses both pressurized air and combustion. To do this, I inject an overly rich mixture of propane or MAPP gas into the combustion chamber, and then add a proportional amount of air. There is a burst disk that isolates the combustion chamber from the barrel until the air/fuel mixture is ignited. The burst disk then ruptures and the projectile "usually a potato" is hit with completely unobstructed flow and is fired. I usually prefer to use it as a purely pneumatic cannon due to the deafening crack that it makes as a hybrid, and also because of how nervous it makes me!