I added LT headers and a 3" y-pipe yesterday. All 4 o2 sensors are installed and hooked up. No CEL. Seems a little more sluggish now like when it was stock.
When I tuned my truck before the headers I only disabled the mds then smoothed the fuel n timing tables. It was a huge upgrade over stock. Now with the long tubes on, I'm not sure where to start on my tune?