hi Tom, thanks for the quick reply. Specific to the two-year part of your statement, I'm going to quote the NHRA rulebook, then ask you a question. First, the NHRA rulebook quote. See specifically the last point, which I have bolded for boldness:
NHRA Rulebook 2023 (General Regulations, Section 21, Page 45) says:
10:5 DRIVER RESTRAINT SYSTEMS
A quick-release driver restraint system meeting SFI Spec
16.1 or SFI Spec 16.5 is mandatory in all cars in competition
required by the rules to have a roll bar or a roll cage. (Permitted in all other classes.)
Driver restraint system must be clearly labeled as meeting SFI Spec 16.1 or SFI Spec 16.5 and be dated by manufacturer. SFI 16.1 or 16.5 3-inch-wide shoulder harness straps folded over and sewn to be 2 inches wide by the original manufacturer in order to fit into head and neck restraint lips/channels are acceptable.
See Class Requirements for additional requirements for Top Fuel and Funny Car.
SFI Spec 16.1 or 16.5 Y-type belts prohibited.
(In cases where the class does not require an SFI 16.1 or 16.5 driver restraint system, the two-year recertification does not apply.)
So, my car doesn't require a roll bar or roll cage, therefore it does not require SFI 16.1 or 16.5 driver restraint system.
However, it is permitted to install and use SFI 16.1 or 16.5 restraints.
Since they are not required (but are permitted), the two-year recertification does not apply.
Now the question: Can the NHRA rule supercede the GRM rule in this case? I have SFI harnesses that are about 5 years old IIRC.