You need to get a rule book, if you are an NHRA member you can download one for free.

However it appears to me that there are no exceptions, this is from the 2019 rule book.

"An SFI 27.1 ribbon-type or mesh-type window net is mandatory on
any full-bodied car running 7.49 (*4.49) or quicker. For full-bodied
cars running 7.50 (*4.50) to 9.99 (*6.39) or if vehicle runs 135
mph or faster, a ribbon-type or SFI 27.1 mesh-type window net
is mandatory unless otherwise specified by Class Requirements."