NASA has a new head restraint rule. SCCA probably isn't to far away. Just something to consider when buying your seat

15.17.9 Head Restraint – Side Impact
As of July 1st, 2007 it is required that all drivers employ a right-side impact head restraint
system. A seat with a “bolster” to keep the head from moving to the right side in an
impact is acceptable. A side-impact head-net restraint system, such as the Racetech
RTViperRP is also acceptable. Note- all side-impact head-net restraint systems must
have a quick-release mechanism to aid the driver in case of a necessary egress via the
passenger side.