A Inefficient Cat Wont Make Your Truck Run Rich, But A Rich Running Truck Will Kill Your Cats. And As The Begin To Clog They Will Start Killing Power And Mileage. Youre Covered For 8/80 On Cats Are You Past 80k? Fix The Engine Issue Before You Start Replacing Cats. And Yes The Headers Will Delete The Cats, How Is Utah On State Inspections? With Headers You Will Always Have Cat Codes Since They Wont Be There Anymore. You Can Try Simulators, Or Downstrewam 02 Extenders To Move The 02's Out Of The Direct Exhaust Stream Which Make Them Think The Exhaust Is Still Being Cleaned. Or Get Uprev Tuning And Have The Codes Deleted