I was just at the Greensboro NC Race Show and spent about 20 minutes with Kris from ISP... The Stealth Head and Shoulder Restraint system is great. It is bolt on and will work with just about any high back alum race seat.
Looks to be very high quality,,, My Stude will have that setup in it for sure,,,due to my size, I may even let them do a custom seat for me too!!...
I can't see how you could go wrong with this setup... I know it is bolt on, but that allows for perfect alignment and height of head restraint.. very sturdy reinforced .125 alum.
Charles