Yeah, you can run a lipo in any gun without a mosfet, a mosfet is just more of a security protocol than anything. It will regulate the amperage coming in and prevent the battery from being too powerful for the gun. I'd recommend to start with a 7.4, as they are pretty similar to a 9.6 is terms of amperage, but give much better trigger response. A 11.1 can cause issues, in my VFC vr16 avalon when using an 11.1 on semi auto my gun will shoot twice because the voltage that the battery gives per trigger pull is too much, and it spins the gears around twice. A mosftet would fix that, so I'd recommend getting a mosfet if you're going to run a lipo, but you don't have to.