So removed the cat and installed a 4" pipe that came with my flowmaster Kit and after about 44 miles I set a code..Well The engine lite came on a I dont have a code reader.
But I lost power from the edge ran fine but felt like stock.I pulled over shut the truck off waited a minute and restarted...edge was working but lite was still on
Is there a fix for this..The thing runs WAY better with this added..Thanks

Check out a finger sticks tread, not sure on a CA truck but I beleive it helps for the fed trucks

Yep, if you are going to run a LLY truck without a cat, and without the stock muffler, the EGR will not work correctly, and it will throw codes. It uses backpressure to feed the EGR cooler IIRC.

Get a Finger Stick and it will stop the codes.