Exhaust O2 Sensor Not Ready

Good morning everyone, I need some help. I have a 2012 mustang gt which is stock except for the exhaust system which I changed earlier this year. I installed a Heart Throb H-Pipe assembly (resonator delete) and Rousch mufflers. This is cat-back only, stock cats are still in place. There is also no tune on the car, it is strictly stock.

Everything seems to work fine, sounds great, etc. However when I went to get the car its yearly inspection for tag renewal today it failed because the O2 sensors came back reading "not ready". There may have been some other "not ready" codes but the only one I am sure of is the O2 sensors.

I took it to the ford dealership for the inspection and they tested it when I arrived for a failure. They suggested I drive it around for a while to heat everything up, which I did (approximately 20 miles). Took it back to the dealership and it failed again.

Any help would be greatly appreciated as they did not know what was wrong and neither do I.

Thanks for any help you can provide.

Well here is an update. After it failed twice, I disconnected the battery overnight and reconnected it in the morning. Drove it throughout the week (about 110 miles) and then drove it around 30 miles the next morning before having it tested again. It failed.

At that point I dropped it off at the ford dealership and they have now had it for 4 days and cannot figure out the problem. They have wiped and reinstalled the computer, driven it who knows how many miles and it still will not let itself be tested. They also told me that along with the 02 sensors reporting "not ready" the EGR heater and EGR sensor are also not ready for testing. At this point they are about to start kicking it up the chain in ford to the higher up engineers for help because none of it makes sense.

Any more ideas?