How common is it for the SHO v6 to get a knocking wrist pin? My SHO has 170k on it and it is driven pretty hard. Before you ask, the rod bearings are new, the valve train is in perfect order and i know for a fact that it is not piston slap. This dull thud (described by me this weekend as a "fapping" noise ) is coming from cylinder 4. The "fapping" noise disappears almost completely when cylinder 4's plug is removed and is not audible above 1500 rpms. This fapping noise seemed to show up all of a sudden one day about 1500 miles ago. The fapping noise has not gotten worse or better even after so many miles driven. In fact, I made a round trip to Lincoln, NE this weekend with this engine. I put about 600 miles on it with multiple high rpm shifts and a highway cruising rpm of 3-4500 for 3 hours each way. WTF could this be? I think I might pull the accessory belts off and take some video this week.