As everyone else has said, it's pretty easy to cut off the old grips and slide the new grips on, just be careful not to cut the heated elements as you do so. A "lift and cut" system works well to prevent cutting into the heater elements.
I went with pro-grips as others on this board had recommended. You lose a bit of heat from the heaters, but also gain a lot of comfort and lose a lot of vibration in the process. A very worth while trade off that I'm reminded of everytime i ride.
Be sure to order two "right grips" though, so they fit over the heating element. Link to purchase on Amazon below....
https://www.amazon.com/dp/B000WO8MKY/ref=pe_825000_114212990_pe_825000_114212990_n_id