http://www.freshalloy.com
or you can always try and contact one of the members whose reputable and has a track car, or has built a track car ; )
JUN was the first in the 8's with the silvia, so you can try out their site, considering they make every part for s13's that you could ever want, from chassis to body to motor to interior to safety to oil to .......blah blah : )
if you want to know about the CA, go to ca forum, and ask for Paul, im sure he'll give you pleeeeeenty of reasons of why His, oh i mean THE, CA is superior ; ) hehe
Jesse.rpi