Stock Setup:  I decided to do some Dyno tests to see how much horsepower and torque my Boxster is really doing.  I did the test at R&D Dyno in Gardena (310-516-1003).  If you're in the L.A. area, I completely recommend them.  There are 3 runs within the Dyno test.  The third run was the best and often the most accurate.  Darrin at R&D Dyno said that the oil temperature is probably closer to the ideal state on the third run.  The tests show a MAX horsepower of 170.3 hp and MAX torque of 152.9 ft-lbs, all at the rear wheels.  All tests were done in third gear.  Below are the Dyno graphs.

PowerFlow Setup:  I took the car to get it Dyno tested again at R&D Dyno.  Tests show a MAX horsepower of 176.2 hp (+6 hp increase) and MAX torque of 156.3 ft-lbs (+3 ft-lbs increase).  In this case test run #1 was the best run.  All tests were done in third gear, with the same Dyno machine and same technician.  From 4500-6800 rpms you can see that the PowerFlow does generate an increase in horsepower and torque, but not as much as I expected.  Below are the Dyno graphs.

The PowerFlow took like 3 hours to install, it was a bit tricky taking out the stock instake box.  I was expecting more of a performance increase, but non the less you can hear and feel the difference.  The Boxster sounds more thoaty and it seems that it's quicker in the higher rpms range, but I don't know if it's what I'm truly perceiving or just because "I know" I have extra hp & torque.  I think for those who autocross their Boxsters, you might see more of a difference in your lap times.  Here are some snapshots of the PowerFlow on my Boxster:

If you are interested in the PowerFlow visit the website.  I purchased mine from ZucZ Peformance Motorsports.