I wouldn't even waste a fiver on paint mate, that manifold looks like a jap crap and without a doubt it will crack
Was going to say the same.
It's not worth it on the cheap for this mate, like billy said it may crack, some weld may fall off, etc etc
If it does it could be bye bye turbo.
Sell it on and get yourself a decent spec r manifold cover.
I have heard some of these cheapo ones don't crack, and it looks like the one you have but I wouldn't risk it.
The only stuff I can think of that "may" work would be
[ame=http://www.amazon.co.uk/Thermo-Tec-Hi-Heat-Coating-Aluminium-12002/dp/B00029KC16]Thermo-Tec Hi-Heat Coating Aluminium 11oz Aerosol (12002): Amazon.co.uk: Car & Motorbike[/ame]
Can get different colours if you google it.
