Upgrades give you special powers and abilities to make yourself and your homies stronger, better, and faster. This is the same as leveling up in a role-playing game, and generally serves the same purpose. All upgrades require a certain respect level, and most have you pay cash also. You’ll naturally acquire both respect and cash over the course of the game; if you’re lacking cash, you can just sit and wait for your hourly income, and if you’re lacking respect, run some missions or diversions, activities, or story missions. Upgrades don’t give you any achievements or trophy’s so buy only want you truly want/need.
My Opinion: Upgrades should make the game even better, and more fun to play. Better customization in a game has been key for a games success.
Thanks again IGN for the information, go check them out, and check me out on youtube. http://www.youtube.com/user/THShmoob26?feature=mhee