Tried out the 4 gun P51 the other day in the arena.  I actually like it.  It has a pretty good size ammo load, 1000 rounds for 2 of the guns, 800 for the other 2.  Not sure if it gives u a performance increase, but I think it may.  I got a 4 kill sortie out of it with 600 rounds and 400 rounds left on the primary and secondary guns.  Not a bad little configuration.I tore the wing off a P51 and shot the tail off a few C47s with it pretty easily.  Also, I have read some stuff about a 6 gun P38, with 6 50cal guns in the nose.  Anyone know anything about this?  The very early P38s carried 4 50s and a 37mm cannon.  It must have been powerful because some 37mm P38s sunk a jap minisub during the early war.