I painted the heat shields over the exhaust manifolds too. It was actually easier than I thought it would be. But they sure smoked like crazy when I started it up after a couple hours. The fumes were strong to say the least. But after a couple minutes it stopped, and in an hour it was cured.
I don't pressure wash it either. I never liked the idea of getting water in and on it. Believe it or not, I used a wire brush, toothbrush, and Armorall wipes to clean my engine. But I literally clean everything I can see and reach, and don't stop till I'm done. Like Allmach said...I'm insane.
Now that it'* painted it will be easier to keep clean.