I am building a Boxster for ITR in SCCA.  I decided to design and build my own strut housings and use Koni 8611 1257 double adjustable strut inserts.  First it helps to have a friend that has a CNC lathe in his garage.  We made the prototype housing yesterday.  I need to make a few adjustments in the height of the strut in the knuckle.  But over all I am very happy with the way it turned out.  I am also going to use a 6" spring instead of an 8" one and also change the upper spring perch. 
Blake