I'd call up as many import performance part-carrying shop that you can think of (local and online) to see who can give you the best prices. Off the top of my head I can think of importparts.com, nopi.com.
You hit the nail with the tuning options. You really can't change anything else other than static fuel pressure and ignition retard amount. If you have a V-AFC you could tweak the A/F mixture just slightly, and if you've got cam gears installed, you could adjust the exhaust cam gear to your liking.
