Since you just bought a new '03 Cobra, you should be entitled to a one year free membership in SVTOA. SVTOA members get a 10% discount right from Steeda. That should put your price at around $179. Could be cheaper elsewhere - I don't know.
I think I got a card to fill out when I picked up my '01. Anyways, try sending an e-mail to Joanne Schultz. She may be able to help you. Her e-mail is [email protected].