Trying to work out if my maf sensor needs replaced but can't find a way to check, it's been a little hard on fuel and there is a tiny amount of black smoke in exhaust fumes, I did try unplugging it and running it round the block but I couldn't notice any difference in the way the motor ran? Is...

im thinking of removing the inside of my freelander 1 td4s cat, I want it to look like it still has one so thought this was easiest option but will it still pass a mot? cant seem to find a definitive answer. also what are the real benefits of removing the cat? Any help appriciated