Based on the SAMTech.edu NHRA Factory Stock Showdown performance numbers from the Lucas Oil NHRA Summer Nationals at Indianapolis, the NHRA Technical Department is reducing the 2019 Cobra Jet 327 supercharger overdrive by changing the upper supercharger pulley from 4.00 inches to 3.750 inches and changing the lower engine pulley from 8.00 inches to 6.938 inches. The 2019 and 2020 COPO supercharger overdrive will also be reduced by changing the upper supercharger pulley from 3.580 inches to 3.250 inches. Additionally, the 2019 and 2020 COPO supercharger rear jack shaft cog pulley will be changed from 34 teeth to 32 teeth and the rear supercharger cog pulley will be changed from 32 teeth to 34 teeth. As a reminder, no other changes may be made to all approved superchargers, including, but not limited to: (upper or lower pulley sizes, gear ratios, cases, rotors, etc.). All other permitted combinations in the SAMTech.edu NHRA Factory Stock Showdown will remain unchanged. These rule changes will go into effect immediately and will be in effect during the completion of the Lucas Oil NHRA Summer Nationals NHRA Factory Stock Showdown SamTech.edu finals to be completed at the Denso Spark Plugs NHRA U.S. Nationals. NHRA reserves the right in the future to make additional rule changes to control performance and maintain parity in the category.