I agree with what has been said, and while this forum is not as active as it has been in the past and certainly gets more going on in the summer (when less Boxsters are in storage), it is far from dead. Just look at all the responses you are getting.
A google search will turn up plenty of boxster forums: boxa, rennlist, renntech, pelicanparts, ppbb, 6speedonline, babblers, etc. However, this forum is easily the best one.