Uh Oh !! Bad knocking !!

Here is an audio of the knock, at speed and at idle. Notice the fluctuation in sound when at speed and feathering the gas. Do you hear compression leakage or something?? Boy, I can't wait to find out what this is. This audio was taken right after it happened... I still haven't gotten back to the car to investigate further. I'll post this text then try to figure out how to attach an audio with the new site format ...