I know this topic sort of died but I wanted to raise one more faq on Porsche and their other turbo 4's they made in the past. I don't think they will make the Boxster turbo this potent but look at the potential.
http://vista.pca.org/stl/968t.htm
This is the last turbo they made.
8 valve SOHC in-line 4, aluminum block and heads
Bore and Stroke: 4.09 x 3.46 in (104.0 x 88.0 mm)
Displacement:182 cu.in. or 2990cc
Horsepower: 305@5,400 rpm
Torque: 369 lb-ft@3,000 rpm
Power to weight ratio: 9.5 lbs per horsepower