Header leak pre-diagnosis?

[Secret Chimp]

I think I have a hole developing in my header. I hear a slight pishy-whizz noise at higher throttle levels, and around the number 1 and number 2 outlet that I can see behind the headshield, there's been this growing light rust stain, like something is blowing it onto the block. I'm thinking this is rusty startup condensation getting blown out of the hole. (The block is aluminum so it's obviously not rusing itself). Further back on number 3 and 4 there is none of this staining. Yay? Nay? I just don't want to waste time getting the likely-stuck headshield off unless I really have to. It's too hot out for wasting time :P

[Soup DeVille]

Rust on a header could mean anything, or nothing at all.

Stick an airhose up your tailpipe (probably best to keep the pressure low), and seal it as best you can, then see if you can hear (or see with the old soap bubble trick) any leaks in the header itself.

[Eye of the Tiger]

I think I have a hole developing in my header. I hear a slight pishy-whizz noise at higher throttle levels, and around the number 1 and number 2 outlet that I can see behind the headshield, there's been this growing light rust stain, like something is blowing it onto the block. I'm thinking this is rusty startup condensation getting blown out of the hole. (The block is aluminum so it's obviously not rusing itself). Further back on number 3 and 4 there is none of this staining. Yay? Nay? I just don't want to waste time getting the likely-stuck headshield off unless I really have to. It's too hot out for wasting time :P

Same thing happened to the Escort. A little whispy tickity-tack sound turned into a BOOAWP BOOOWAP BOOOWAAAAHHHHHHHHHHHHHHHHERAGAH as the manifold continued to separate from the head and burned holes in the plug wires, rendering two cylinders unoperational.