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4" vs 5"

  1. 06-07 LBZ & LLY Duramax Powertrain
    I have decided to make the first big mod to the truck, a new MBRP exhaust. Now I need to know everyones opinion of what I get with the 5" that I would miss with the 4". This will be down pipe back, removing the cat. My goal is performance, MPG, better sound. I don't need to wake the dead with...