I did wonder with the tune, if codes were being inhibited somehow. Obviously, the exhaust codes would be inhibited, because all of it is gone now. I wonder if the exhaust is where a code would be generated. I will be sure to ask him. It has barely been noticeable, until now. Today, I am getting a rough idle and a noticeable loss of power. But, still no CEL and no error codes. I will give an update when I get with the tuner, unless anyone has another idea of what to try/check.