Looks like -5 jacket at 9.99 in IHRA and 9.0 (6.0) goes to -5 jacket and pants, collar. 9.99 in NHRA for everything.
NHRA used to let Stock-Super Stock cars use different clothing requirements since they are all OE floor and firewalls. That appears to have gone by the wayside and everything is ET based for them as well.

If the results don't match the theory, change the theory.