I think one of the biggest problems most gamers have with Rifts is the MegaDamage system. It kind of works, but in reality, at least for me, it sucks. Here are two thoughts I have on it:
1. There's too damn much of it. If megadamage was limited to mecha and major monsters, it would be fine. But when any average headhunter can go buy a set of megadamage armor, it just cheapens the effect. I have no problems with a tank or glitter boy having and dealing megadamage. I think it's just dumb when a guy wearing some plastisteel armor suddenly has it. Same with a pistol that deals megadamage. No reason for it. A rail gun, yes. A pistol you wear in a gunslinger holster? Heck no!
2. Purely for aesthetics, I'd love it if it was more like Savage Worlds!. Give the item a Heavy listing, so it can deal damage to big creatures, without having two sets of hit points. There is no reason to have MDC, SDC, and hit points in the same game. Really. Just give everything one stat. If it's something like a SAMAS suit, give it armor 50 (Heavy), etc.