The AHFS is used to review and evaluate runs in Stock and Super Stock for possible horsepower adjustments. The data used during the review for possible increases in hp is  from the 1^st National or Divisional event through the final National or Divisional event of the calendar year. Runs included in the AHFS database are limited to final qualifying runs (Q data) and all elimination runs (E data) at all NHRA National, Sports National and LODRS events. (At events where class eliminations are run, class elimination runs are included in the AHFS database as part of the "E" database with exception of first round of class eliminations. The first round of class is part of qualifying and therefore is part of the "Q" database.) The "Q" data and "E" data files are the official data gathered by the NHRA timing system and processed through the NHRA Information Technology department. NHRA "Q" data and "E" data are the only data files used for the AHFS. No runs made during exempt events, National Opens, test and tune, time trials, 1/8^th mile events or races within a race (i.e. Jegs Allstar eliminations, Stock / Super Stock Combos or other races that are not part of a season long points championship) are included in any review. 

The following procedure is used in reviewing run data:

Parameters used for reviews:

1. Transmission type: Reviews made with manual transmission combination will be reviewed separately from automatic transmission combinations & visa-versa in Stock Eliminator. Reviews made with manual transmission combination will be reviewed separately from automatic transmission combinations & visa-versa in Super Stock Eliminator for those cars competing in section 12A (with the exception of SS/AH), 12B, & 12C. All other cars competing in sections 12D – 12G are reviewed together with manual & automatic transmissions. 
2. Body platform: Reviews are only in effect for the specific car model being evaluated. The body style is generally classified by the OEM auto manufacturers' definition of "platform", i.e., the Camaro and Firebird body are both based on the same platform and therefore considered the same with regard to body platform classification.
3. GT & base SS classes: GT classes will be separate from base SS combinations & visa-versa.
4. GT/FWD & GT/RWD: FWD bodies will be separate from RWD bodies & visa-versa.

Runs of 1.200 or more under the index will be adjusted following the event. Adjustments are rounded up to the nearest full horsepower even if the fraction is below 0.5 horsepower. As an example, 2.15 horsepower is rounded to 3 horsepower. The quickest run, by the engine family being reviewed, is used to determine the adjustment percentage. Once the need for an adjustment is determined, the sliding-scale formula, based on a percentage of horsepower, is used to calculate the horsepower increase:

Any contestant who posts an elapsed time that would result in an immediate horsepower or index adjustment, must report to Technical Services for validation of the run. Any contestant failing to report to Technical Services for validation of the run for (weight, fuel, etc., including “driving by” the scales), shall be disqualified from the event and suspended for a minimum of six (6) months. The event shall be charged against the driver’s annual quota of scored events with zero points awarded. The NHRA retains the authority to recognize the validity of any race result, or time recorded, in cases where there may be attempts to discredit the run.

The decision to adjust horsepower or to reduce the index will be at the discretion of the NHRA Tech Department.

In addition to reviews resulting in a horsepower increase, a competitor may request (only one request per competitor, per review period.) a review for the purpose of a decrease in horsepower factor or index adjustment. The request must include eliminator, year, model, engine size, advertised horsepower, factored horsepower, and class; to be eligible. (NHRA AHFS Horsepower Request Form).

Once an engine family receives a horsepower increase it is not eligible for a decrease.

• Runs from previous years will be used to validate a change is warranted

The decision to adjust horsepower or to increase the index will be at the discretion of the AHFS Committee.