You're right.. It does look like the MSP would be alright in STX. I'm still going to look for an official ruling on the car but that WOULD be a tough class. STX is full of IntegraR's and WRX's. Hmm.... Although DS is also so not really sure which way to go with this one. The Falkens are a little cheaper then a race tire and will probably last alot longer so maybe for expense reasons alone, I'll try STX this year.
Thanks All. And if anyone finds an official ruling, I'd still appreciate the link or the info.