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  1. Introductions
    Howdy, new 6.6 2500HD owner from California, behind enemy lines! I'm anxious to learn what I can do to increase performance here in this state while remaining "legal" for the emissions sniffers, aka Tailpipe Nazis. I got my 2015 used about 6 months ago. It has 94k miles and just started...
  2. General Discussion
    I just hit 75k miles on my 2015 LML and just received a P0420 code. Code “P0420” - Catalyst System Efficiency below Threshold Bank 1. Can someone tell me this means that I need to change out catalytic converter or just the NOx sensor on Bank 1? Thank you for any help I can get on this. Rey
  3. 911 Problems Forum
    I instalked a mrbp 4 inch down pipe back last night with the stealth 2 quadzilla. I downloaded the update for the no dpf. I drove it to work today and now i have the cel light... So i checked it and tge code 0420 popped up. Should i drive it.... Will it limp? How do i fix this?