Check out
www.986forum.com -lots of guys into getting a few more HP from their cars.
If I read the desnokling correctly, remove the engine vent behind the drivers door (1 small screw and some clips), pull out the long plastic accordian intake hose and remove. that simple.
Having moved from an "improved" 911SC to a Boxster (nonS) and now looking for another SC type car, I can say that out of the box, the Boxster outperforms the SC. Even modded like my 911 was, its edge over the Boxster was limited at best. The Boxster would benefit MOST from improved suspension geometry. Lowering/stiffer springs and more negative camber are the best improvements to be made to the Boxster. Reliability aside, had I done similar mods to the Boxster as i did to my 911, the Boxster would have been faster at the track.
The drawback to putting a cage in the Boxster is open air fun. I loved my 914, especially with the top off. After putting in the cage in the 914, driving with the roof off felt confining. Not nearly as much fun.. plus you might worry about your knoggin, or your passengers, finding the cage the hard way. On the plus side, having ridden in a Boxster with a cage, it really helps stiffen up the chassis.