There are only 3 photos I could find showing 4 cannon. Lots of talk in other forums about this saying it didn't last long in service use. A few different reasons such as problems with gun heating and weight effecting maneuverability being 2.
One is of a delivery to Malta where they needed cannons to replace the breeches that the limestone dust infiltrated and wore out more quickly. They added them to these carrier launched replacement aircraft and deleted the .303's, since they used only 1 .303 in service at Malta and had plenty of them. When launched they were loaded with only 60 rounds in 2 of the cannon.
One is of a 2nd SAAF aircraft.
The last is of supposedly a wing command gent who kept his 4 cannon.
Basically rare as hen teeth.
So let's do a variant with just 2x20mm. That would be lighter, and would demand accurate shooting. Could be fun.
I don't think the extra 2x20 would affect maneuverabilty too much; the added weight would be equivalent to about 20 gallons of fuel wouldn't it? Go here for a performance report of the SpitVC with 4x20, in which states there is no difference in handling: http://www.spitfireperformance.com/aa873.html
). But of course, let's not put
the 4 cannon spit in the game if there were only a few actually in combat. The 2x20 would
be fun tho.