question for guys that race often

ok, from the NHRA rule book,any car running 13.99 or quicker is required to use a helment meeting snell K98, 2000,2005,2007,or SFI 32.1a, 31.1/2005, 41.1a,41.2a or 41.1/2005. page 97 of new NHRA rule book. the book, states, 9.99 or quicker must wear a full face helment.