You are in so-cal and you can't find somewhere to buy parts? You must not be looking hard enough. Where did you get everything for the eclipse =P?

Try these
www.ipsracing.com
http://www.heeltoeauto.com/
http://store.yahoo.com/yhst-1408381693991/

Intake mugen, j's, comptech
For header look into toda, smsp, hytech, rmf, dtr, mugen.
A quiet exhaust I run is RS*R, you can also look into getting kteller custom piping. Mugen twin loop is suppose to be quiet as well. My rs*r was quieter than the twinloop on my friends prelude.

These are just a few suggestions, search around and check out the sponsors