To put in my .02 here, I used to have a 90 Integra. The only time I noticed a difference was when I heat wrapped my intake, and took air in from behind my bumper. I know I'm using a honda to compare, but this car was where I picked up most of my knowledge from. Either way, an engine, is an engine.
As far as "true cold air" and "cold air" intakes, the "true" cold air comes from outside the engine compartment. As said before, cold air is denser than hot air, and in an internal combustible engine means more power. N2O is basically a cold air "rush" into your engine, and that why you make more power with it. To truly have a "true cold air" intake, you would need to insulate the air charge from the hot ambient air in your engine compartment to notice any kind of a power gain, i.e. heat wrap your intake tube, and seal off your filter from the engine compartment air and take it in from the fender area. HTH. Later.