haha i never thought of that, i used a utility knife and a chisel, lol, well, i actually did think of using a drill but i coulnt find the 3/4 or 7/8, 3/4 i would have used because then there is not so much chance of drilling on the end of the bars, there is some red plastic (well red on mine anyways) that i guess just extended from the grip heater, but my grpis still heat up, but use a drill, it took me about half an hour for each side using a utility knife and a chisel (the chisel i used to cut some of the red hard plastic than was harder to get at on the upper part of the whole, iff you know what i mean, but I did get them on, haha, after an hour.