2008 chevy Silverado
4.8 v8
had put on aftermarket air intake
no problems
finally had headers, hi flow cats, larger piping, flowmaster muffler
after exhaust was installed I started getting engine codes p1153 p1133 I believe a p0420 at one point before I cleared. I now have loss of power black sut out the exhaust. im presuming the vehicle is now dumping fuel. ive changed the o2 sensors has not resolved any ideas????

 

You need to get the air/fuel ratio recalculated bayou can't throw headers on and expect the stock tune to keep up with it. Needs a custom tune