desnorkled my Boxster last night.
Wife wanted a "sportier" sound (amazing, you have the perfect car and you always want to tweak it more).  Aftermarket exhaust is too expensive, and this is free so decided to try it.
Directions - got the directions with pictures from this forum, but I did it a little different.  I loosened the whole case, then took a slim screwdriver and pushed the plastic tabs out of the metal clips.  Then the whole thing, case & grill came out.
It was VERY hard pulling the plastic (snorkel) tube out.  But I finally got it.
Reversible? - for those who asked, yes it can be reveresed if you don't like it.  Just push the plastic tube back in.
Noticeable Difference? - it was true what they said on this forum, don't notice it till you get over 4000 RPM.  I did not hear it till I was in 2nd gear (over 4000 rpm) ready to shift to 3rd gear.  Definitely a "throatier" sound.  It did sound pretty cool.
Hurt your car? - I don't think so.  maybe water getting in there with a high powered jet (like a car wash), but you would be a fool anyway taking it to a car wash.  Spoke with Mechanic, he said the only problem is that your Check Engine Light will come on because it senses a problem with the intake.  So you will not know when you actually have an engine problem as your light is always on.
Is It Worth It? - It is free, takes 10 minutes and is reversible.  what have you got to lose?  Just don't expect a huge difference.  Just a 'sportier' sound when you are "gunning" it.
anyone who would like to comment on this, please reply back.  Thanks.