Thanks very much guys. haven't got any more done yet, but might have something to show tomorrow.
Jelmer, for exhausts, I use different techniques depending on the required result. In this instance, after studying pics of the actual exhaust on KF183, I painted the front section semi-matt black, with a very light dry-brush of silver over the extreme front, where the small pipe is.
The main section was then painted with matt black, mixed with a very small drop of silver and, when dry, lightly dry-brushed with grey. The exhaust staining was done with my friend's wife's eyebrow pencil (!), drawn on lightly then smudged along the fuselage.
The rusty coloured exhausts are done with a build-up of various colours, using a stiff brush to dab on the surface if a texture is required, as in my Beaufighter build in the MTO GB.