I had this done to just get new cats and O2 sensors. I had my old cats and O2 sensors in the trunk as I just installed new cats and O2 sensors with new engine build. They traded me old parts for new never touching my car except they would not do the trade without a reflash of the pcm. They need such to prove a car was done and satisfy the recall on the vin. I brought my stock pcm with me, installed it, they flashed it, and I then removed it and put my tuned one back in. They had no problem with this but would not release the parts to me without flashing the pcm first. They took the cats but told me I could keep the old O2 sensors. Here’s the pics with the stuff at home, cats are sealed and in my attic and sensor kit still in the box.