Curious, what would TC3 (or MMO, UCL, etc) do to a cat over time? I've got a Toyota PU w/100K and NC has been doing computer emissions testing for several years at the annual inspections. So far, no problems. If using the TC3 starts causing cat failure, will it show up during these tests? Secondly, if its been used regularly (every second or third tank)and then stopped for a prolonged time, will it "burn off" or clear up in the cat?