So I've been having this fluttering noise, when the engine isn't under load. This was the 10 minute diagnosis by a good, but not Infiniti specific mechanic. Does this sound like anything else that G37's do?

DIAGNOSTIC LABOR
Notes:
Confirmed that there is a fluttering noise heard from the engine when no load is applied to the engine or the RPM is held at 1100. The noise is coming from the driver side head. The noise can be heard from the rear of the head. At this time the valve covers will need to be removed to inspect the camshafts and valve clearance if the valve lash is out of adjustment the camshaft will need to be removed to install new tappets. Service information states that if the valve lash on the intake valves are out of spec the corresponding cylinder head and vvel assembly will need to be replaced as they are non serviceable items.

 

Sounds about right from everything I've read.
Seting up one of the vvl heads is beyond tho scope of anyone but the factory or an experienced specialist

 

I'm still not sure it's a valve. I may get in there and see if I find a vacuum leak or some loose piece of plastic or something. They didn't do too much more than stick a listening probe around, I have a strut tower bar and it was a free '10 minute diagnostic' while I had some other work done.
Thinking someone who has a lot of experience with this motor knows just what it is.

The other question, if it is a valve out of adjustment, is it critical? We used to have miatas when I wrenched on them that people were always bringing in for the valves. The hydraulic lifters would not quite pump up enough, and tap. Customers always thought the engine was going to go. They were fine just as is, or you could run engine cleaner through it to clear out the passages in the lifter and they would usually be fine.

*I do see some information on the VVL making a noise from the driver side, and an ecu update. I'm going to try to find some video to see if mine sounds the same