Lets see now. For 2011 all SCCA drivers SHALL wear a SFI 38.1 H&N restraint. With the Isaac I own not SFI rated I'll buy (not happily) a Defnder which frontal load equals the Isaac & HANS while also greatly reducing the lateral load which the HANS does not do. No right side net required.

It's a laugh that the CRB/BoD recomends a right side net while not allowing the Isaac because of the one release rule. Yes I understand the window net rule to keep the arms inside the car. < This rule came long before the H&N restraint.

Dito on the silly unsuported head "restraint flaps" that may be added to the seat. Watch one video of the head during a crash you'll understand. The flaps resist minimal lateral load.