What is this PAX thing anyway?
Current PAX Factors can be found here
The PAX factor attempts to equalize the field by assigning a time penalty for each run. The time penalty is based on the car’s potential performance. Developed by Rick Ruth, the PAX factor system is in wide use across the country.
This Index was developed by Rick Ruth and reflects study of results from well over 500 nationwide Solo events including, the Tire Rack® Solo National Championships, National Tour, Alabama Region, Atlanta Region, Chicago Region, California Sports Car Club, Central Florida Region, Equipe Rapide (Florida & Texas), Great Lakes Solo Series, Hawaii Region, Houston Region, Midwest Divisional Series, Milwaukee Region, Minnesota Autosports Club, New England Region, Northwest Region, Northern New Jersey Region, Oregon Region, Philadelphia Region, Rocky Mountain Series, San Francisco Region, San Diego Region, South Jersey Region, St. Louis Region, Tri-State Sports Car Council, Texas Region, Washington DC Region, Wisconsin Autocrossers Inc., and many, many others
CMC maintains some additional PAX factors for Karts.