So to make a long story short last year I bought an 08 GT500 from Texas and had it shipped to North Carolina where I live. It had basic bolt ons: 2.6 upper pully, JLT intake, BBK long tube headers, off road x, and Magnaflo axle back. It had an unknown tune on it but I suspect Bama. I put a set of BBK high flow cats on it because I knew I would need them for the visual inspection. So this takes me to where I took it in to be inspected. All 3 o2 sensors showed not ready. I had not disconected the battery and had put about 1000 miles on it so I suspected it was in the tune. I buy a Bama X4 with tunes for life from AM and they send me a tune for my modifications. I drive it almost 200 miles and still have the same problem plus EGR is not ready now. I noticed when using a scan tool the cat monitors are not even showing up so after 2 phone calls and 2 more tunes they now show up on a scan tool. I have now driven the car 125 miles making sure to follow the drive cycle that shoud set everything to ready. I still have all o2s and EGR not ready. I have driven it normal, hard, and as easy as I can and still no luck. I was hoping someone would have an idea. I have no codes and no pending codes. I have heard the headers could be causing the problem and restricting the exhaust could help but I havent tried it yet.