I'm not sure if you can get that now. Its pretty much just a letter on Team SVT stationary that says "In addition to your cars Certificate of Autheticity, SVT is sending you this letter as official documentation that your Cobra Coupe was painted with Mystic Clearcoat Metallic.In 1996, there were 7496 cobras produced and only 2000 of those were painted Mystic. Your Mystic Mustang (serial number) was #208 of 2000 with that option."
I condensed it a little. But, its really just a letter, as opposed to the SVT Cobra certificate that has signatures and all.
The guy I bought mine from had both framed, so they are here in my computer / nascar room.
Go on that Mystic Cobra website, contact the guy that runs it and see if he can cross reference your serial number to which Mystic number you are. And on another topic. The paint for these has come down some. You could probably get the whole car painted for 3 grand.