Lovely extractors on my Civic

Lovely extractors on my Civic. It's been a while since I've really modded anything in the car. This one was my pledge to keep it as standard as possible. However, due to unforseen circumstances, I had to replace my extractors. Since I was replacing them, why should I keep it standard?

Funny, when the extractors a.k.a. exhaust manifolds were installed, they were chrome and shiny. After a few days of use, they started turning gold. I'm still wondering about the phenomenon. The last time I changed the exhaust manifolds were in my old Wira with the 4G93T engine. The colour was again chrome, but once used, they turned bright red on one trip to Genting. Didn't manage to get a photo of the glowing red manifold. After prolonged usage, they started turning blue.