The Maverick Region of the Porsche Club of America is having their annual time trial at Motorsport Ranch this Sunday. I believe it will be on the 1.3 course (http://www.motorsportranch.com/1.3-road-course.cfm).
Sign up at www.clubregistration.net. There is a limit, so I am not sure how they will decide who gets entry, but if you're interested, then at least sign up.