SpankedYA!

Sounds to me a valves or even an exhaust leak.

Darkelvis

I'm going to work on the car again tonight, I'll check the valves then.

tranceminister

I would man. I got my Z6 head rebuilt by a machine shop too and he made sure to note that I needed to adjust the valves myself. I adjusted my valves to factory but I have one of those damn 59300 Comp cams/Zex cams in it so it's still noisy as hell.

Ravage70

could be the plastic behind the cam gear
doesnt sound like valves to me because it repeats itself very fast

Koby

Sounds like lifters if you ask me. Clean the sons of bitches out, or replace them.

I've had luck in the past with different cars quieting down if you switch oil from dino to synthetic too.

leed

Deff. sounds like valve lash in the video IMHO.