I just replaced the grips on mine as they were getting a bit ratty over time. I can't for the life of me remember the brand, but make sure they are gel grips, they are DAMNED comfortable.
handy hint for removing them, stanley knife and cut the f*king things down the middle. Putting them on, firstly make sure that you dont mix up the grips, the left one has a smaller diameter one than the right.
Putting them on, on the left side just put a lot of water on the bar and the grip, then grip the bar with your left hand, and use the weight of the bike and the palm of your right hand and force it on. its a bit harder on the throttle grip as its a larger diameter and often has the little plastic lugs to stop the grip coming off. Same idea applies there, but may require more messing about.
Took me about 30 minutes to put the right grip on, and 10 minutes the left, and remember, keep the things WET.