Youd need to De-Pbo it, change the config , then PBO it back up again.
TBH, im suprised DKM havent done something about it, its a common complaint that thier chally 2 is understrength.....
....i wonder what the hell thier BETA testers were thinking..... :-\ the chally 2 is one of the most heavily armoured tanks in the world (more so than the Abrams AFAIK)