I'm surprised, all of the advice you've been given is correct.

Your idea that a cooler intake charge is easier to burn is backwards..A warmer mixture probably has the fuel more totally vaporized and thus easier to burn. As said above, the real power increase is that cooler air is denser air, so you can get more oxygen and fuel molecules into the engine, thus making more power.

The open element air filter sitting under the hood isn't the way to more power. Ducting cooler outside air into the filter is.

Unless you are a class racer who is looking for the next hundredth of a second, switching thermostats won't do anything.

The most power for a combination is obtained when the coolest possible air is inducted along with the fuel in optimally sized droplets. When the fuel is completely vaporized before it gets into the engine, it actually reduces power because the gaseous fuel takes up room that could otherwise be occupied by oxygen molecules. Thus the droplets make more power even though they are not as easy to burn as completely vaporized fuel.

R.