Hmm the plot thickens ......
After a quick google the picture of the Epic Tirant does not look the sames as your frame at all:
Tirant TT cable routing:
After a bit more digging it looks like it was their Synergy model that best matches yours ... The frame only (below) was a custom build with canti tabs but there is a full bike build that is more like your frame.
Looks a far closer match - Custom frame:
The Synergy is our longest running production model with new features for 2005. We have introduced a tapered 35mm-50mm downtube to increase the power transfer with out any weight penalty. Another new feature is the integrated dropout/disk mount which ensures maximum strength and alignment where you need it.
With re-engineered geometry for longer travel forks, the Synergy is now even better equipped for extreme back-country fun!
The 3/2.5 titanium tubing produces a lively ride with vibration damping qualities found nowhere else. You will appreciate the difference after one ride!
Each frame is handcrafted, one at a time by people who care about quality. After the frame has been welded and quality control checked, a durable scotch-bright finish is then applied. The Synergy features straight gauge, seamless 3/2.5 titanium tubing throughout and 6/4 titanium dropouts and small parts.
Details like these set Epic apart from the competition.
Finally to add a silver lining ........
It could have been a completely custom bike using the Synergy as a basis a la: