Hi Fred, I took 2 exhaust to the local radiator shop and they stuck it in the radiator vat (cleaner) over night then flushed with high pressure, they look like new now, only charged me $5.00 Same stuff they use on engines, didn`t mess the chrome, But if any part of it is alluminum it will eat it up, so far I haven`t saw any in an exhaust. Doug D.