At least for short term performance. Still skeptical about the thing
   taking long term heat.

   http://www.rx7club.com/showthread.php?t=752927&highlight=aluminum+rotor

   They made 830ish on a turbo 2 rotor with the aluminum rotors. Videos on
   youtube.

   Rob Woods

   Yes the trick is making them hollow to cut the weight and having cooling
   passages.

   Paul Lamar
   --

They say that that they weigh 3.2 kg loaded. 7 lbs.

Rob Woods.

That is a two pounds savings. Not bad for a solid aluminum rotor.
An exact copy less the one pound gear would be about 2.64 pounds.

Paul Lamar