Had a problem years ago with a mouse plague. Anyway the pacemakers came out worse for wear, very rusty. I removed them, spent $50 had them sandblasted and bought pacemaker blue paint from my local exhaust shop. ( yes that's what's it called and it's original) anyway, heated the pipes with an oxy till you see the change in the steel, not red, not even close, just a change you will know what I mean when you do it. Then paint good even coats on extractors while hot and presto, came up awesome.