I was quoted 530 for exhaust pipes, back box and sports cat. Sadly on DCi models the sports cat is embedded in the manifold (new manifold is the only way around which doesn't seem very sensible). So just ended up with the main exhaust system for a nice tidy sum.
Has improved mid range torque a lot, which doesn't really help town driving, but motorways are much more fun. Boot it at 70, let the turbo spool and watch the speed climb.
Was very quick too, have pics and a vid if anyone's interested.