A friend of mine is in the process of rebuilding his 13B-REW and he told me that it is possible to get the rotor housings friction coated and the rotors cryo-treated and heat-treated wouldn't these thermal processes tighten up the clearance on the motor? also i read in a recent issue or turbo magazine that they cryo-treated piston rings for a supra and that it was harder for them to file it down due to the process. will that have a negative affect when rebuilding motors?

 

Someone posted this place in a thread a few days ago, they do the cryo treatment.
Sounds like it would work, don't know about cost effective though.

http://www.rotorsportsracing.com/