mobil 1 Has just enough zinc to get by with a flat tappet IF you have a good quality cam and lifters. I dont think the cat will be affected too much and if it does eventually wear out the cat, hey you can always replace the cat. the aftermarket cats dont cost too much.[relatively speaking]. I remember in the 'old days' a new car from the late 70's the cats would only last about 5 or 6 years anyway [with regular mileage ]. So if this is not a daily driver, I'd think the cats would last awhile. You will need to keep the 'tune' really tight though. IMHO.
