Except for modifications authorized below, Stock Category cars must be run as specified by the factory with only standard equipment as defined by these Rules. This requirement refers not just to individual parts, but to combinations thereof which which would have been ordered together on a specific car. Any other modifications or equipment will place the car in Street Prepared, Prepared or Modified Categories as appropriate.

Option package conversions may be performed between specific vehicles of a particular make and model, but only between configurations from within a particular model year. Such conversions must be totally complete and the resultant car must meet all requirements of this section.

Taken right outta the SCCA rulebook.