From the HSK reg book
GSR 4:11 ROLL CAGE (ET 9.99 TO 8.50Secs)Roll Cage: All cage structures must be designed in an attempt to protect the driver from any angle, 360-degrees and be fully welded. All 4130 chrome moly tube welding must be done by approved TIG heliarc process; mild steel tube welding must be approved MIG wire feed or TIG heliarc process. Welding must be free of slag and porosity. Any grinding of welds prohibited. Additionally, roll cage must be padded any where the driver’s helmet may contact it while in the driving position. In Competition eliminator where SFI Spec on chassis is required, padding must meet SFI Spec. 45.1
Your'll need to get the right company to make and fit.
The one from custom cages is just a roll bar for
GSR 4:10 ROLL BARS (ET 11.99 to 10.00Secs)All roll bars must be within 6-inches (152 mm) of the rear, or side, of the driver's head, extend in height at least 3-inches (76 mm) above the driver's helmet with driver in normal driving position, and be at least as wide as the driver's shoulders or within 1-inch (25.4 mm) of the driver's door. Roll bar must be adequately supported or cross-braced to prevent forward or lateral collapse of roll bar. Rear braces must be of the same diameter and wall thickness as the roll bar and intersect with the roll bar at a point not more than 127 mm (5-inches) from the top of the roll bar. Sidebar must be included on driver's side. The side bar must pass the driver at a point midway between the shoulder and elbow. All vehicles with OEM frame must have roll bar attached to frame; installation of frame connectors on unibody cars does not constitute a frame and therefore it is not necessary to have the roll bar attached to the frame. Unibody cars with stock floor and firewall (wheel tubs permitted) may attach roll bar with 150 mm (6-inch) x 150 mm (6-inch) 3 mm (0.125-inch) steel plates on top and bottom of floor bolted together with at least four 10.0 mm 3/8-inch bolts and nuts or weld main hoop to rocker sill area with 0.125 (3.2 mm) reinforcing plates. All 4130 chrome moly tube welding must be done by approved TIG Heliarc process; mild steel ( or ST51) welding must be approved MIG wire feed or TIG heliarc process. Welding must be free of slag and porosity. Any grinding of welds prohibited. See illustration (PIC. 18). Roll bar must be padded anywhere driver's helmet may contact it while in driving position.
Adequate padding must have minimum 1/4-inch (6.35 mm) compression or meet SFI Spec. 45.1.
I commisioned Thor racing to source one of the above for my car to run in the HKS series, they went to custoncages who used both my car and Pete's aero to design the one they are advertising, Thor were supposed to have exclusive market after funding the design using our 2 car.
After the damage to my car and their dealings with the situation Thor decided to keep away from them.
As of yet i haven't had my car with the roll bar passed to run in the HKS series so am not able to state it would pass scruitineering.
The 2 people that give the ok are:-
DRAG RACING CHASSIS INSPECTORS
SFI Approved Chassis Inspectors:
Geoff Martin-01608 674121 (Mobile): 07811 678798
Mark Norton-01865 400812 (Mobile): 07881 456314
These guys measure tube thickness, designs and check welding, they approve cages built by reconised companies like Websters, Housier and Andy Robinsons far more often that bespoke ones.
At the end of the day if your going to the trouble of having one it needs to be able to protect you if needed.
Mine has bolt in door bars and is made of CDS, bolts to plates welded to the floor etc.
I could post up some picture if you want but dont think its realy what your after as its no good for a 9 sec car