2009 R6 Stacks

[smaxwell]

Hi - first post on here.
I was wondering if anyone knew exactly what material the yamaha stacks are made from? Having taken apart the air box on the bike i've seen they're made from some sort of polymer (rather than an aluminium alloy as I presumed), but must be fairly heat resistant as well?
I'm designing some velocity stacks for a Formula Student Racing Car which is using the R6 engine but not using the variable stacks that come with the bike. The calculations have been made and the correct length for harmonic tuning has been found for revs at max torque for the car.
Thanks to anyone who can help,
Steve

[MELK-MAN]

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).