I will be doing this myself in the next week or so. I have order a K&N universal kit #RE 0930. As far is it looks, it is just a matter of taking the air box, and all the piping out. The K&N should just slide on at that point. (there is a 3 inch pipe just sitting there) Finally there is some sort of air temp sensor, what I am going to do is drill a hole into the K&N, big enough to accept the sensor, I am then going to silicone it to prevent leaks. All in all, it seems like an easy project. I can't wait to hear the s-charger make some noise!! Now, if I could only afford a nice sounding exhaust!!
I'd stick with a K&N filter that goes in the box. That stuff is there to give the engine Cold-Air Induction. If you take it out, the engine will be drawing air from the engine compartment, which is hotter than the outside air. Colder air with fuel, is more combustable than hot air. Which you might gain a couple of hp from the cone filter when the engine is cold, because the engine won't have to draw air through the piping. When that engine compartment gets hot, you're going to lose that gain and them some.
If you won't more hp from a cold-air induction setup, get Ram-Air Induction.
Well. I finally got the cone filter installed on my s. I first removed the air box, then I got a cone filter that had a 3 inch inlet, and was 7-1/2" long. The filter fit snuggly on to the mass air flow sensor. I then got a drill bit, and drilled a hole on the top of the filter, and inserted the iat sensor into it. The whole job took about 20 mins, and the filter fit great (just long enough). My driving impressions are a little bit snappier throttle response, a bit more power(slightly noticeable) but most significantly, an increase in supercharger noise. It now sounds like there is a giant dentist drill in the engine compartment. (quite entertaining)