I would add two of my other favorite Porsches. 944 S2/968 or a 944 turbo. I'm not a track guy but know a lot that do.
Here's a video of Wheelers and Dealers. Two episodes. The Boxster crowd may not appreciate as much since it's not Boxster related.
They purchase a 944 turbo for 2800 pounds and spend about 2000 pounds on Suspension, Roll cage, Chips and track wheels and turn this into a track car. The chips alone increased WHP from 230 to 261 WHP. The 944 turbo has the balance and weight of the Boxster but they have more power. Too ad they didn't add a test pipe in place of the cat.
https://www.youtube.com/watch?v=s1jDZKdwKGI
https://www.youtube.com/watch?v=lLEJSBOABy0 Part 2