Jad wrote:Welcome.

Welcome on the slippery slope

Enjoy building your race car, it's a great experience and I would do it again.
Don't get discouraged, but Jad is right.

Per example my 911 started out as a $16k donor car and ended up being ~$45k race car and I can think of more to do. But, it is now exactly what I always wanted it to be: a reliable, lightweight, fast and fun do drive race car.
Some may disagree with me, but I think you are doing the right thing by going directly to a full on race car or at least as far as the Boxster Spec Rule Book allows you to go.
The beauty with "spec racing" vs "check book racing" is someone has already done the research and you don't have to figure out which shocks, springs and other mod works or not. But there is no such thing as cheap racing.