joeoby78

I noticed yesterday after work and then again this morning when I start my truck ('05 Silvy w/5.3L) that there is a pop, just once as it turns over and once it gets going everything is fine. I ran a scan with my programmer and have no codes, and the plugs are fairly new, NGK TR6's about 6-7K on them. Was running NOS but last time I had it tuned I had the tuner put the timing back in it in preperation for a timing controller and haven't sprayed it since. I recently went from shorties with cats to long tubes with resonators, my tuner forgot to tune the rear O2's out so I stuck them back in to keep the engine light from coming on. Now, I occasionally get a Catalyst system code, but I just delete it and go on down the road. Should I take the rear O2's back out, are they causing a conflict?