This link shows you how to remove the driver's side vent to get to the air intake tube. There are 3 tabs on the vent that need to be pressed in, as well as the one screw that holds the vent housing in. Same procedure on the pass side to remove vent grilles.
http://www.pcars.us/10min-boxster-de-snorkel-hack-t3401.html
If you remove the air tube on the driver's side, you'll get more of that intake growl noise that some people like.