first off i would like to say that there was a time in my life that i thought i knew a lot about 2nd gens. a couple months ago i found this site and come to the relization i know NOTHING!!!!
anyway the question was... How much do you really get out of an air box. as opposed to just having the cone filter. does the box really make that big of a differance??

 

cold air is dense air. dense air holds more oxygen. so there are two methods of getting more air into the motor. one is less resistance, the cone filter accomplishes this with more surface area. the other is drawing in cooler air from outside the engine bay. thus the factory snorkel. but you can build a cold air box around the cone filter and draw in outside air giving you the best of both. some will even route tubing infront of the radiator, etc instead of boxing it.

 

The cone filter w/o a heat barrier makes a lot of difference and the addition of a barrier helps even more.

With just a cone you've take away the restriction of the stock box but are now subjecting it to engine bay temps. When I built my barrier I saw temps drop by 30 to 40 degrees F.

Ambient T., Airbox T., Spread, Drive type
Before
50, 100, 50, city, lots of sitting @ lights
50, 110, 60, warm, city short drive
60, 120, 60, all stop & go
After
43, 58, 15, from cold, across town, 15-20 min
43, 58, 15, sitting for 5 min.
43, 79, 36, heatsoak after ~1hr. Sitting
43, 63, 20, warm, across town, 15-20 min