Hello together I bought an occasion car 9 months ago. A few days ago a mechanic discovered by chance that the exhaust was modified (including welded). I wanted to ask myself if it is possible to determine by an expert the age of a weld seam? If so, how exactly would this be? I must somehow prove that the modification was made before the purchase and I haven’t changed anything on the exhaust since purchase – otherwise I have bigger problems… Or do you have other ideas like I can prove that? The previous owner says he didn’t do anything and I would have made it. Thank you for your help and greetings.