I was wondering if replacing my stock air inlet system (filter, box, ducting) with an aftermarket system (open air filter) was ultimately a trade off.My car now has more air intake capability and more dyno horsepower, no disputing that. But with the hood down and ambient air temps over 105 degrees and my engine bay temps in front of and around the air filter at 140 degrees, I'm wondering if the insulating properties of the stock set up offsets the performance gains of the aftermarket system.I did the following experiment to prove insulating the air filter from the engine bay reduces the temperature of the air entering the engine significantly.As Sgt Mac would say, "elementry my dear Dr. Watson."I mocked-up an air filter cover that completely surrounds the filter, side and rear, so that air only comes in at the front. I positioned this insulation shield flush up againt the forward bulkhead cutout. The shield is about 1" larger in diameter than the filter. Material used was 1/8" corregated cardboard.Previous measurements over the past three weeks showed an unshielded 25-35 degree increase in air around the filter than ambient.With the shield inplace the air temp around the filter was only 10 degrees above ambient after 40 minutes of city driving 35-60 MPH. The outside of the shield was warm to the touch but the airfilter was neutral to the touch. So what does all this mean, first, I think that using a shield at the strip should be helpful. Around town, don't know because the experiment didn't last long enough (at least a couple of tank fulls). Second, raisng the hood after a race dramatically reduces the air filter temp to ambient in less than 45 minutes, maybe even sooner, I only checked after 45 minutes, even though the engine was still too hot to touch. Regardless, I had fun doing this.