My 2019 rulebook says "For full bodied cars running quicker than 9.99 or 135MPH, a window net is mandatory. SFI 27.1 mesh nets need to be replaced every 2 years. In Stock class requirements, it says "...a net is mandatory in vehicle requiring a roll cage" "Requiring", not using. That's 9.99 and quicker. That's relevant to all door cars, not just Stockers.

Years ago there was language that said if it has a cage, it has to have a net regardless how fast it is. That has been gone for a long time.

As far as a funny car cage is concerned, obviously a funny car, dragster or street roadster in going to use arm restraints instead of a net. Years ago, they allowed drivers in door cars with a funny car cage to use a restraint for the left arm in lieu of a net. They got tired of policing that and it didn't last long.

Currently, a door car requires a net in front of the front funny car cage bar to protect the area between the funny car cage and the A-pillar bar. Typically they are small - a foot or less - but they need to be there. There also needs to be smaller bars incorporated in the outer part of the funny cage cage structure to keep the helmet entirely inside the outside plane of the cage. If there is any question, they will run your helmet around the inside of the cage while using a straight edge across the outside of the bars. They don't want the helmet to get out beyond the straight edge.

As a result of some incidents last year, some new hardware and mounting hardware has been developed for mounting the nets. This stuff is mandatory in Pro Stock and Pro Mod, but for any new installations, I would certainly look at using it vs. the old seat belt buckle hardware.