Sonic carb cleaning?

[Silverlegacy]

I think the standard exhaust doesn't have the link pipe welded to the front of the can but uses some kind of packing to make the joint slightly flexible.  Some do blow slightly out the gap at the front of the can but not normally enough to be a problem at MOT time.

I did just a bit of gun gum in there too, to try and seal around it but it became brittle as gap pretty small.
The MOT guy never said anything, so either didnt notice or its just not a problem.
I have seen a picture someone put on here a little while ago where they cut there old exhaust up to show the internal workings, so think it just degrades over time and causes a slight leak through that gap.