I have a Toyota Celica that has a 'dealer fitted' Toyota twin stainless steel exhaust. Unlike the original pipe which would have been placed to the right of the car, this has a double exhaust that is now placed centrally at the rear.
I have informed my insurance that its dealer fitted and they have said that it doesn't matter, but I'm worried that, should I need to claim at any time, they'll change their mind. So the question is, as its dealer fitted, is it still classed as 'standard' or is it a modification?

Thanks for looking!