As the result of runs under the Automatic Horsepower Factoring System (AHFS) 1.20-second under policy at the Mac Tools U.S. Nationals, the following changes have been made.

The horsepower rating for 09-10 Dodge Drag Pak, entries with the 370 cubic inch engine and a factory rating of 385 currently rated at 404 has been increased by twenty two horsepower, to 426 horsepower; for Stock Eliminator.

The horsepower rating for 2008 Ford Cobra Jet, entries with the 330 cubic inch engine and a factory rating of 425 currently rated at 475, has been increased by sixteen horsepower, to 491 horsepower; for Stock Eliminator.

The horsepower rating for 2010 Ford Cobra Jet, entries with the 330 cubic inch engine and a factory rating of 500 currently rated at 534, has been increased by eighteen horsepower, to 552 horsepower; for Super Stock Eliminator.

NHRA's 2011 Automatic Horsepower Factoring System outlines that any run of 1.20-second or more under the index will receive an immediate index decrease or horsepower increase. These changes are effective Sep. 6, 2011.