NASA National Class Rules for GTI-Cup (Adobe PDF Format)
 

2005 Northern California GTI-Cup Supplemental Rules (Adobe PDF Format)
With approval from NASA, the Northern California GTI-Cup racers have adopted, beginning in 2005, a limited supplemental set of rules to the National Class Rules.   Note: These are supplemental rules for all GTI-Cup races for Northern California points only.  Cars with these modifications will be illegal as GTI Cup cars in all other regions.
The reasons for the rule changes are basically: 1) make the cars a bit more fun to drive by some small performance enhancements (weight drop and limited modifications) and 2) to accommodate the aging nature of the cars in terms of the diminishing availability of OEM parts and engine blocks.