H RA ▁refused ▁to ▁enter ▁into ▁Non - Dis closure ▁Ag re ements ▁with ▁the ▁delay ▁box ▁manufact ur ers . ▁Once ▁submitted ▁for ▁N H RA ▁appro val , ▁and ▁pay ing ▁the ▁fee , ▁delay ▁box ▁manufact ures ▁were ▁not ▁allowed ▁to ▁make ▁any ▁changes ▁in ▁design ▁for ▁any ▁reason ▁without ▁res ub m itting ▁to ▁the ▁N H RA ▁for ▁re - appro val ▁and ▁pay ing ▁another ▁fee . ▁To ▁obtain ▁the ▁N H RA ' s ▁appro val , ▁delay ▁box ▁manufact ur ers ▁had ▁to ▁accommod ate ▁the ▁N H RA ▁by ▁making ▁any ▁design ▁changes ▁the ▁N H RA ▁mand ated . ▁ ▁Ess entially ▁the ▁N H RA ▁was ▁now ▁design ing ▁delay ▁boxes ▁by ▁proxy . ▁Furthermore , ▁drag ▁rac ers ▁were ▁prevent ed ▁from ▁using ▁any ▁delay ▁box ▁they ▁made ▁themselves ▁at ▁home . ▁This ▁is ▁changed ▁the ▁face ▁of ▁drag ▁racing ▁in ▁a ▁huge ▁way . ▁Trad itionally , ▁grass ▁roots ▁drag ▁racing ▁was ▁where ▁rac ers ▁could ▁build ▁their ▁own ▁ch ass is , ▁engine , ▁transmission , ▁differential , ▁vehicle ▁pl umb ing ▁& ▁vehicle ▁w iring , ▁etc . ▁ ▁Sk illed ▁rac ers ▁could ▁build ▁their ▁own ▁race ▁car ▁with ▁their ▁own ▁hands ▁from ▁parts ▁wherever ▁they ▁acquired ▁them . ▁R ac ers ▁were ▁not ▁required ▁to ▁buy ▁anything ▁pre - made ▁if ▁they ▁didn ' t ▁want ▁to . ▁Those ▁days ▁became ▁history ▁almost ▁over night . ▁V irt ually ▁any ▁rac er ▁innov ation ▁( elect