it could also be an injector easy way to check squirt washing up liquid in the injector ports with injectors still in, you will soon see if it is or not,im not sure on how the exaust is fastend to the manifold but where the joint is between the 2 have engine ticking over and run your hand round the joint,another test you can do is wait for engine to go cold and start it up and look for exaust smoke and dont tell me it dont smoke on start up its britishand its made by rovers,