Why does everyone seem to go for off the shelf exhausts???
Went dont you try JP Exhausts based in MAcclesfield, they have an excellent reputation and I know many happy customers. Besides if you should have any problems they will always sort it F.O.C. regardless of how old it maybe!
They do a variety of tailpipes, singles up to 5", rolled in or rolled out ends, twins, ovals, dtm, slash cut.
They do work for TVR, Caterham for both exhausts and manifolds. They also do classic cars and do Stratstones Ferrari and Aston and Porsche sports systems.
I was up there the other day and are making me a polished stainless manifold for my 2.0 XE 16v engine which is in my nova. They are using a SBD high torque manifold as the template and making it in 1"5/8 bore. It should look well nice once done, once its got nice and hot it will go a gold colour!
As a rough idea they charge about £150 for a back box, and roughly about another £250 for the system. The systems are made to fit on the car, so during the process of making the exhaust its on and off the car a fare few times! If i remember the 172 exhaust splits into 2 from the manifold to the twin cats?? so it could be dearer!
Ultimately, you wil not be disapointed with there work!