thanks for that, turns out the car is gonna have to have a visit to renault at some point soon to get this fixed.
basically what it is, one of the straps which holds the exhaust up has broken, so the exhaust is drooping quite significantly and there is a hole in the join between the cat and the pipe between cat & silencer.
it would have been better anyway if id been able to borrow my friends ramps but he wasnt around today
yet more expense!