There doesn't seem to be a lot of info out there about how the Street Touring classes have changed for 2018. STF no longer exists, those cars have been split up between STX, STR and the new STH class. The only Subarus left in STX are the BRZ's' I don't know what the best way to get the word out is but I saw several WRX's with STX on them at Event 1. The cars are listed in the 2018 Solo Rules Draft A at https://www.scca.com/pages/solo-cars-and-rules with the Street Touring classes listed starting at page 159. The Street Touring rules are at page 69 with the biggest change being that ecu's are now open for tuning.