I found this,

11.49 1/4-mile (7.35 1/8-mile) or quicker:

-A 5-point minimum roll bar on a fixed roof car (t-tops okay as well if in place while racing) from 11.49 to 11.00 (7.00 1/8-mile). If the hardtop / t-top car has un-altered floors, firewall and frame rails (wheel tubs are okay), then the 5-point roll bar is good til 10.00 1/4 mile (6.40 1/8-mile). Convertibles require the 5-point bar from 13.49 (8.25 1/8-mile to 11.00 (7.00 1/8-mile). The rollbar must be constructed of minimum 1 ¾ inch o.d. x .118 inch wall mild steel tubing, or 1 ¾ x .083 chrome moly tubing. The roll bar can be bolted or welded to the floor, see diagram for specs. Roll bar must be padded anywhere the driver's helmet may contact it while in the driving position.
See diagram below.

The 5-points are:
-Main hoop; 2 "down bars" (bars that go from the main hoop rearward to the trunk floor/hatch area. These can be straight or bent like a "package tray" style, search for photos); Welded crossbar for belts (can't be removable); Driver side door bar (can be a swing-out. Many put a passenger's side bar in as well (6-point) because it strengthens the car on both sides, but if you have subframe connectors the difference may be minimal).

-Protective Clothing (SFI jacket with a 3.2A/1 rating, no expiration date)

-5 point harness (up to date, they must be replaced or re-certified every 2 years)

-SFI-approved flywheel and/or clutch (no expiration date)

-Screw-in valve stems

-No tint allowed on window except factory

10.99 1/4-mile (6.99 1/8-mile) or quicker:

-5-point roll bar is still okay to 10.00 1/4-mile (6.40 18-mile) in hardtop / t-top with un-altered floors, firewall and frame rails (wheel tubs are okay). If the floor and/or firewall has been modified, then a full roll cage is required beginning at a 10.99 e.t. or any vehicle running 135 mph or faster (regardless of e.t.). The roll cage must be constructed of minimum 1 5/8 o.d.x .118 mild steel tubing, or 1 5/8 x .083 chrome moly tubing. Roll cage must be padded anywhere the driver's helmet may contact it while in the driving position.
See diagram below.

-Convertibles require full roll cage at 10.99 and quicker.
See diagram below.

-aftermarket axles with positive retention (c-clip eliminators)

-Transmission shield SFI Spec 4.1 at 10.99 and quicker or 135 mph and quicker (blanket is okay, no expiration date)

-Harmonic Balancer SFI Spec 18.1 (no expiration date)


9.99 1/4-mile (6.39 1/8-mile)/ 135 mph or quicker:

-Roll cage is required on all vehicles at 9.99 and quicker or any vehicle running 135 mph or faster (regardless of e.t.). The roll cage must be constructed of minimum 1 5/8 o.d.x .118 mild steel tubing, or 1 5/8 x .083 chrome moly tubing. Roll cage must also be certified by NHRA every 3 years, and have a serialized sticker affixed prior to participation. The cage must be padded anywhere the driver's helmet may contact it while in the driving position. This style of cage is good til 8.50 1/4-mile times, then a funny car style cage is required.
See diagram below.