I did it a while a go for the Dora, modding vertical convergence so that at around 250m Mg 151 shells would cross the gunsight instead of the stock 600m. It was a world of difference, i didn't have to guess where the shells would go, just put the gunsight on the target and boom. Also, it was much easier to hit when the aircraft was rolled to 90°, as the shells fly closer the the aim line. Anyone with exentended WWII sim time knows that convergence is very important to aerial gunnery.
Too bad i can't use that setting online, as right know i miss half of my point blnk shots because shells fly over the enemy cockpit.