So much guessing and wrong information. Your exhaust manifolds have temperature sensors in them and will alarm if get to hot. If you had a RInda then it would tell you the temperatures the exhaust manifolds are running that how I know mine. Cat manifolds run hotter than old style manifolds even with catalyst removed (great job!!!!). Your initial temps at idle are perfect. The temps you refer to coming off a plane are fine unless they never drop back down to what you said at idle. How long for temps to drop? are they still hot a week later sitting in your garage??????? Manifolds have ton of iron it takes time for them to cool back down. Your thermostat is 160F. At idle probably will never fully open. On a plane running 3500 rpms the engine will be at least 160F, thermostats control minimum temp not max. You will not be able to put your hands on your cat manifolds even without the cats coming off a plane. Your IR is probably cheap POS. You have to shoot the manifolds within an inch or you are taking the temperature over a 8" area. IR temp will only be correct if dull black as the emissivity defaults to one. In the end I don't think you have any problem at all. If it makes you feel better you can't hurt the manifolds they are beast, the catalyst elements are fragile POS, again great job eliminating!!!!!!
