i think this might be a track by track thing, i was told that the tech folks here in Spokane want the seat back tied to the cage, oem or not.....from the 09 rule book, page 271, section 6:2, upholstery, seats "the drivers seat of any car in competition must be constructed, braced, mounted and upholstered to provide full back and shoulder support. The drivers seat must be supported on the bottom and back by the frame and crossmemeber. Except as noted in SFI Specifications, seats must be bolted with four bolts (and nuts and washers) on the bottom and one bolt in the rear into crossbar; all bolts must go into frame or crossbraces."