hi was chatting to my local garage about a decat and he told me the mot on diesels is not an emission test as sorts, it is a test which fires a beam of light or laser across the tail pipe to see how thick the gas is the more light that gets through the better and that is how they test the emissions so there should be no problem with a decat.
he has had a couple of golfs in which have had an egr delete kit and decats and they have all passed the mot with no problems.
