Thanks for the answers and pointers.

Took it to garage for inspection. Manifold etc fine. Proper mechanic said no sign of rust, system was good quality and sound was coming from the baffle box (internal) but it was not blowing. Said he would replace it if I wished but suggested that I just leave it and get it rechecked prior to MOT (which is in June!) - what a contrast!

So no new car needed, not even a new exhaust...but a cautionary tale...don't believe your local tyre/exhaust centre when it comes to jobs/prices...I have used 'Selecta Tyre' for many years (Escort/Mondeo) but they have lost my custom for two cars (wifes Fiesta) and gained a story which I shall retell to others thinking of using them.

Thanks again for the info and comments, very helpful.

I use one garage a ford dealer that i trust and has never lied to me but having worked in the trade im well aware of the con men out there kwik fit are still the worst a sad but true fact many garages do this they prey on ignorance and lack of knowledge ive heard some wild stories and quite a few have been posted here

At work the womans corsa had a management light on she took it to a friends garage who fleeced her for over £500 in repairs the light came back on and she said the manifold was cracked he had tried a temp repair it failed thats why the light was on i took a look no sign of repair or damage to the manifold he claimed to have serviced the car and renewed the coolant yet the oil was dirty the filter was old and the coolant was weak i plugged in my code reader it showed a faulty o2 sensor she bought two sensors and the service items £127 total took an hour to do the lot and the car was fine that was a supposed friend i felt sorry for her so took nothing for doing the work yet he wanted her to pay for a new manifold and cat to fix a non existent issue he would have taken £1000 to do £127 of work off her some people have no shame