Right so all being said I've painting it, the paint I've used is from a local friend who uses the same on more classic cars. The paint is designed not to flake or peel and takes temperatures up to 700'c.
He showed me some of the exhaust headers he's done in his workshop and some existing cars that he did a few years ago and there was no huge scratches or scrapes to speak of but it did look quite bad on the side exit systems as it goes quite dull after about 2000 miles. That being said after a few thousand miles through rain and the winter it won't last to well being exposed so no win either way.
I've got 3 coats on now and it's surprisingly hard wearing for out of a rattle can. I also sprayed up a waste piece of steel I use for jacking up outside and gave it the same 3 coats just to see how easy it would be to scratch off. I scraped a stone over it and it just left a mark unless I forced it across and a key and a screw driver cut it back quite easily as it would with any paint.
I only do about 2.5-3k miles top a year which is pretty much dry weather only so I'm confident it'll last quite well. Fitting is this weekend and then around December time the car is coming apart underneath to be undersealed and rebuilt near new so it'll give me a chance to re visit to see how well the paint has held up