I bought the rig needing a hg so I don't know what it drove like before. I have the timing set to 6-7 degrees with the terminals jumped. The truck runs well although I am getting a the nonsuffencient code. The exhaust sounds really restricted, like it labors i. The upper rpms. Maybe I'm just not used to this engine but I would think it should have a little more power than it does. What will removing the cat do besides a cel. I don't care about the rear o2 reading dirty as it does not affect the drive cycle.