I make WWII aircraft models (1/48) and I have never been satisfied with the way the exhaust pipes look. I’ve tried just about every kind of “metal” paint, including ModeMaster’s burnt iron and I’m still not happy with it. I don’t have access to the real metal ones that you can get as aftermarket so I’m stuck with painting.
I have not gotten any but I know my LHS has some, www.northstarhobbies.com, or if you have a LHS close you can check them out or see if they can order in. Of course you can check out online shops…
Having spent a good hunk of my time as an A&P working on and around warbirds I’ll put forth some observations. About the only time the exaust systems look metalic is when they’re brand new. And then they have a wide range of colors - dull silver to almost metalic black. After a few hours of operations, they start to rust with the colors ranging from a blackish brown to a dark orange with out any sort of metalic coloring. Suggestion, if you have a car that is more than 2 or 3 months old - go out and take a look at the exhaust system under it - take away any dirt and it will pretty well match what is on an airplane.
I’ve got Rust color in MM, Humbrol, Testors (small bottle) and even a couple of bottles of Pactra. They’re all a slightly different color (tone?) and all get used on a regular basis on the exhaust systems or my models.
qmiester covered it pretty much. I add a dash of very fine powder or rust chalk to rust colored paint to add some rough texture to the metal. Looks more convincing as an exhaust pipe.