most of them that make it is only the titanium axle back as someone said...or just the Ti Muffler and tip. a full Ti catback would not be afforadable and easily to get.
reputable companies that offer Ti component exhausts that i know of so far are:
HKS (Ti series)
JIC MAGIC (505SUS series)
5Zigen (Pro Racer series)
Tanabe (ultra medallion)