We just finished putting my LS1 bmw back together for the 3rd time today and my buddies were conserned about a metallic tapping sound coming from the motor. I told them it was normal and like that before and they disagreed. Here is a video of the sound
It is at its worst point when blipping the throttle. Specs are in sig.

 

You really have to listen hard, but I hear what they and you are concerned about. No it's not normal....I don't know specifically what is causing it, but I'd check pistons and cylinder bore out of round specs? ..i.e. piston slap?

valve train geometery?

All I know is yes....it's making unusual noises, and it's gonna take some work to figure it out.

 

Any chance it could be a bent pushrod? My engine ticked after I bent a couple. Does it through any codes?

 

I second the bent pushrod, my driver side ticked like crazy, then one day I was bangin gears and i threw a cylinder misfire code, had the valve cover pulled and i totally broke a pushrod. Threw a new one in, no tick whats so ever.