I believe all these devices require drilling holes in the helmet, HANS, Hutchens, and D-Cell. I think the first two are required in NASCAR and F1 so they are drilling thier helmets also. Both companies have done extensive testing on sleds and if you believe what they say, you are much better off with one of these devices than without. Their customer service folks will help you make your decision. I had some very mild chafing on my groin and I think I was bordering on being too tight, however, as I said above I didn't even notice it once we started.