SECTION 6: NHRA PRO MOD DRAG RACING SERIES (4TH Paragraph) (Page 5)
Lockup converters are prohibited on supercharged and turbocharged combinations. Lockup converters are permitted on nitrous-assisted combinations. Overdrive units are prohibited on all combinations. A 1-to-1 relationship is mandatory in high gear for all transmission types. Automated
electric, automated pneumatic shifting devices permitted prohibited on all transmission types; must be controlled by preset engine rpm and/or time functions only. Each individual shift must be a function of the driver and controlled manually. Iterative transmission staging device permitted on converter cars. Manipulation of transmission or converter pressure or volume other than at the starting line is prohibited. Pressure manipulation control must be disarmed upon the release of the transbrake or any other device used when launching the vehicle. See General Regulations 2:12, 2:13, 2:14.