This is a crappy video from my iPhone, but this is what rod knock sounds like. I towed the car to a trusted shop to get a diagnosis. I was hoping it was only something wrong with the valve cover being hit, but no, it was my worst fear; rebuild the engine.
Rod knock happens for a few reasons, but for me, it was oil starvation. 1200 miles before this video, I had the KillerBee Oil Pickup installed by IA Performance (who is awesome btw). New oil change and everything. But, somehow within those 1200 miles I had lost almost ALL of the oil in the pan. Thats about 4.2 quarts worth. Upon further inspection (once the engine was removed), the oil return from the Turbo had a missing clamp. While this shouldn’t be a problem, I think that when the turbo was under higher pressure it started to leak. It must have leaked a lot. Rock knock also meant that I spun a bearing, which disintegrates the bearing into tiny bits, all inside your engine. The oil filter was FULL of bearing material. This means it needs a new turbo, or at least rebuild it.
Lesson learned: check your oil every time you fill up for gas (or at least ever other time)!