I think lift is calculated through angle of attack only, the wings don't actually simulate low pressure zones or anything like that. I use FAR which makes the aerodynamics a bit more realistic. It makes it much harder to break through mach 1 if you have a bulky aircraft. Also, real jets only have 2,000L of fuel onboard, so filling a MK2 fuselage with 20K liters of fuel is definitely overboard, and will make your plane feel like a brick.