the factory aero kit is usually a three piece kit: side skirt, front bumper and rear spoiler.
the side skirt in the factory aero kit is usually a perfect lazer cut fit.
The aftermarket stuff is usually off and can have annoying gaps. There is tiny gap on one of my side skirts which is noticeable because the the mud guars needed to be removed in order to install the side skirt. I should have sent it back but I didn't feel like dealing with all that for a tiny gap. I would have ordered teh factory style but I really wanted the more aero 911 style like in the picture above^
instead of the rounder factory look for the boxster:
factory Boxster sideskirt (based off the 99-01 911's)
after market GT3 MK II look (based of the 02-04 911's)
