some real high tech stuff... plastic
the throttle bodies are in between the motor and the airbox. It doesn't have to be all that resistant to heat. Why would you NOT use the variable stacks?? it only increased the HP of the midrange of the bike by about 15hp, and rounded out the top a bit too over the 06-07 r6 that has the same engine. (very MINOR changes, nothing that warranted significant hp increase).