So, bought my first LBX kits. They're really damn fun, but I knew there was no way I wasn't going to modify them. The shoulderpads on Buster are from HG Buster Gundam, a long with some other pieces. I made his waist a double balljoint/replaced the hips, too. On Proto, I painted his main antenna what ever piece the grey of his body (because painting yellow is the biggest pain in the ass), obviously gave him the shield + the rifle, made his sniper attach on to his back, did some general painting fixups, made his abdomen joint a double balljoint, and, though it isn't that noticable, made those waist flap pieces move so his hip articulation isn't hindered forward/back (he can kneel, now).
Mind if I ask where you get yours?