Hate to post again on same forums but here goes:
BTW car is 2006 M35, it has vq35de with 268k miles
The sounds seems to occur from 2000 to 3000 rpm range when accelerating, and they are very distinct "clicks". Could it be indication that the timing chain and tensioner needs to be changed? For background; a couple months ago the mechanic said they found pieces of the timing chain tensioner in the oil pan but they were unable to determine if it were pieces from a prior change. For what its worth carfax found no such service ($40 down the drain ) Also, I have codes for p0011, p0021, and p0340, and I heard the first two relate to timing chain tensioner. I have a recording of the sound and can provide more occurrences of said sound.