I've done 5 track days in the FiST now. 4 in California and 1 in Colorado with more planned this year. Trust me, the stock FiST can do very very well on any track. At Laguna Seca, I was able to keep up with a Lexus ISF in the corners, but he would easily blow me away on the straights. The best compliment I got was from that driver. He told me he could see me slowly creeping up on him in some of the turns. He even let me pass him cause I was literally on his @$$. Also, BRZ/FRS have no chance against the FiST. See exhibit A:
https://goo.gl/photos/kKdH9M6tzUBxUDC48
https://goo.gl/photos/kKdH9M6tzUBxUDC48