The claim that snorkeling is counterproductive is somewhat controversial...
Finally: Dyno charts of de-snorked 986S!!!
I can't find the link to the thread at the moment, but Jake even touts the desnorkling of a 2.5l boxster spec car.
Take caution before it's know-all end all.
~~~ It's also true that our car stock has a cold air intake- albeit a rather inefficient one. I did not believe it was that bad until I actually saw the maze with my own eyes. Don't except a massive jump rocket in horsepower, but you would indubitably free some horsepower up.