You have hot air under the hood both ways.

But....if you do a dyno with COLD AIR blowing directly into your air intake...believe me....there is a difference.

Makers of ram air/cold air systems still haven't found a way to truly test according to air flows like when you're going say 130mph (at which I achieve a full 4 lbs extra boost on the dial on my SC car).

What they do is take an industrial fan and blow it into the front of the car....which accomplishes basically giving you colder air to the intake during the dyno test. Still....they advertise on average 5 to 10% with this cold air difference (some even more).

Their advertised hp gains are therefore not the full benefit of what can be realized at high speed. One could argue of course that this IS realistic for posted speed limits.

I think you really have to design something that comes to the front and fully funnels cold air in.