I did a similar setup last year in early summer as this K&N Apollo (No snorkel):
http://4bangerjp.com/forums/index.php/topic,4744.msg38064.html#msg38064.
Forced in to getting the components from one of those 4 cylinder street hotrod online retailers and maybe one or two things at auction. But its probably roughly the same thing as this K&N design. If I had known about the K&N setup, I would have gone with that. But maybe they came out with that at the end of '08 or the beginning of this year.
My filter is obviously closed off in the plastic casing and I also added Thermotec materials to the tubing and intake manifold for what its worth. Haven't taken the intake air temp, but its probably as close to ambient as I'm going to get.
I'm not using a snorkel but that would probably work well too (Not a lot of Jeep "submarine" opportunities nearby but maybe I'm not trying hard enough; Nearest water, though, for me is the Pacific Ocean and a couple of urban lakes).
The oiled cotton filter is enclosed and inline which is all good. But the filtration isn't likely to match your standard paper filter. But then again, maybe these Apollo-type deals with the cotton gauze filter are a fairly reasonable match with a snorkel since the snorkel height supposedly allows for a bit cleaner intake air charge on average. Maybe you are on the right track adding one of these Apollo deals to a snorkel.
I'd say the performance with my pieced-together intake has worked for me on the low end -- 1000-3000RPM, especially after I added the Bosch III injectors (Maybe running a bit lean prior). And the engine recently passed CARB emissions also. I don't wind it out a lot because the Borla cat-back I have can wake the dead at high RPM if you are in the city; highway on-ramps are a different story and over 5000 is no problem. Good luck and thanks for the link showing the K&N product.
