I'm sorry I didn't catch this after the first event, but Street Touring cars should not be included in the Indexed Street Tire class. Street Touring cars are given their Index factor based on them using street tires. Other classes are based on the assumption they are using true autocross tires ("R" compound for Stock, Street Prepared and Street Modified and Slicks for Prepared, Modified and Karts).
It is inherently unfair to those cars in the Indexed Street Tire class (by a lot) that are not Street Touring cars. Street Touring cars should have their own Category in the results (lumped together) and scored on the Index or they can be included in the "Sportsman Group".
H's & K's,