Some say there is heat soak with the metal intake. I don't think that is as big a deal as getting cool air from the out side to the open element filter. I have a AEM brute force and I am happy with it. Now during the summer if I sat at a light for a while the temperature on the air coming in would rise pretty high. After I got moving it would come down.
I just don't think that the hot metal would thansfer enough heat to the air coming through it. With the velocity of the air and time it is in contact with the intake just dose not seem to matter if it is metal or plastic. If you go to there web page I think they discuss it.
The theory is based more upon aluminum than any other metal from my understanding. Aluminum dissipates heat extremely well, that's why most modern computers today use aluminum casing and heat sinks. Same applies here it helps take heat away from the engine all the while cold air comes through the tube quickly passing all of this. I've heard of engine temps dropping 10 degrees or more and also heard that a degree dropped is power gained to a point....... I have an air raid plastic and I haven't been to happy with it. I do not have the throttle body spacer thought that I've noticed a lot of people have. I'm going to either switch to an aluminum based or get the throttle body spacer. Keep you informed on temps and which I felt was better.
I have the K & N plastic intake. I went with it mainly because I don't show off the engine I also like knowing that compared with a aluminum intake I will have a slightly decreased temperature of air. The facts are that metal absorbs heat and even thou aluminum dissipates heat quickly it does still absorb heat. The differance is probably very slight but I know it, and that makes me feel that much faster. Once again the difference probably isn't even measurable its all a state of mind.
yes aluminum will dissapate heat well. but aluminum will heat soak quick as well. if one part of the aluminum is hot the whole tube will be hot. stainless will also disipate heat. i suppose if they could make one out of copper it would be even better since it heat soaks less than aluminum or stainless. i have used aluminum,stainless and plastic and my intake inlet temps were very close.