Just take your OEM exhaust off (and the metal link plate, metal holder and disc washer), unbolt the plastic bits and send it to a local powder coating company and get it painted. It's very easy.
Cost me £20.00 for the powder coating (yes Twenty Pounds)...
Or if you don't want to use your own exhaust, I bought a BRAND NEW one off eBay for £50 including delivery (on a Make an Offer bid). Cheap as chips.
Took 24 hours and refitted it back on the bike next day, as I was able to drop it off and collect it myself. You can have the choice of Matt Black, Satin Black or Gloss Black. I went for Satin Black exhaust and Matt Black everything else.
If you buy a second exhaust muffler off eBay it just means your bike is never without an exhaust while you paint the other one.
That does look smart... wish I had thought of that... the buying of the second exhaust