Modified Classes – Overview All classes will require that the vehicle be currently registered, tagged, and insured. Modified (Stock) Any Cougar with more than 3 changes from original factory configuration while retaining a stock appearance. This class is intended for clones or tribute cars with factory-appeariing upgrades. A Marti report will be required for entry into this class, which will be judged according to Street Stock standard pertaining to the model being cloned.