[Gravy]

Where did you get the knock sensor from? I would try warrantying out the knock sensor and try a new one. I didn't see a question to the "Mechanical Noise" issue. Any problems with the car we need to know about? Exhaust leak like you described shouldn't give you a knock issue, and not that high. Did you have to change the wire going to the sensor or no? If not, are there any breaks, weak spots on the wire that may interfere with the signal?