and they have never peeled or cracked. I have hit close to 900 celcius on my egts many times. The down pipes will be several hundred degrees cooler than the exhaust manifold. I also have my turbo turbine housings coated the same and they are holding up good. Turbine housing would see higher temperature than the down pipes. If they did peel, it would not get sucked back in. Exhaust does not flow backwards in the downpipe.