just thought i would relay this new info to u incase this might cause u a problem on your nxt mot if u have an aftermarket exhaust........this has come from vosa from immediate effect..
"testers will now assess the level of exhaust noise at all engine speeds required for the exhaust emmisions check.we have also made a slight amendment to the reason for rejection,which now makes it clear that the comparison is with a similar vehicle with a STANDARD silencer in average condition"