Mid to low 11 based on hp and weight. If not it's the driver and u can fix that with practice. Nhra track rules may be of interest
A roll bar is mandatory in all cars (including T-Tops) running 11.00 to 11.49, in convertibles running 11.00 to 13.49, and in all dune buggy vehicles running 12.00 seconds and slower. The rollbar must conform to the diagrams referenced in the NHRA Rulebook.
A roll cage is mandatory in cars running 10.99 or quicker or any vehicle running 135 mph or faster (regardless of E.T.). In full-bodied cars, with unaltered firewall, floor and body (from the firewall rearward, wheeltubs permitted), running between 10.00 and 10.99, roll bar permitted in place of roll cage. In convertibles running 10.99 or quicker or exceeding 135 mph, roll cage mandatory. Cars runing between 7.50 and 9.99 must have chassis inspected every three (3) years by NHRA and have a serialized sticker affixed to the cage before participation. Plating of chassis prohibited for all cars manufactured after 1/1/2003. Rear-engine dragsters must conform to SFI Spec. 2.7A; vehicles running 8.49 to 7.50 and/or exceeding 180 mph must meet appropriate SFI Spec for body used. All others must conform to specs for body style used, as listed in General Regulations 4:11, 10:6 of the NHRA Rulebook.