I believe the downpipes are the hardest to find parts needed for the Tri-Y setup. The manifolds and hangers have been reproduced but to my knowledge, the downpipes never have been. Because of this I had mine fabricated.
They are not the most difficult exhaust fabrication project but typical of a Tiger, there are clearance challenges.
Even though the special exhaust hanger is required for the passenger side, the driver side front connection is the most cramped.
The other three connections are not too bad.
Another thing to remember is on the passenger side the rear pipe must angle a little forward to clear and allow removal of the starter.
Although fabrication could be done out of the car with the manifolds bolted to a head, it would be risky because of these challenges, I decided to install the manifolds and have the car towed to the exhaust shop.
Attached is a photo taken of mine during the process