Re: Not all need to be recalled.
There's something wrong with it, if it blows a cloud of soot. Get it fixed.
The soot is caused by a combination of driving style and injector effectiveness. As the injectors wear, the fuel dispersion gets worse, leading to incomplete combustion and more soot (although there's an element of soot even with new injectors), but unless you have a gentle right foot this soot doesn't accumulate in the exhaust. When it accumulates, that's when hard acceleration and faster exhaust gas flow ejects the soot in a plume.
Injectors are very expensive to replace at £200-400 per injector, so there's no reason to change it if you're happy with the performance, and if you normally drive with a gentle right foot, you'll have an exhaust pre-loaded so that you can lay smoke like a destroyer when passing cyclists. What's not to like?