Hey thanks for the response, but what I'm having trouble figuring out is how do you diagnose the noise under the noise engine? Is it really noticeable?

It is noticable, but under some circumtances only. I recommend you to try WOT at 2500-3000 rpm on 4th gear.

Any update on this? I'm getting the same described issue but doesn't happen under acceleration. Most of the time this happens when blipping the throttle during a downshift or coast. Also, I determined that this only really happens around 2000rpm, more likely on the lower side of 2000. Engine internals are stock but I have an intake, I'm wondering if it's anything to do with the a/f ratio, maybe a side effect of the intake allowing more air in to the MAF. I'm considering dropping the stock air box in to see if this resolves the issue. I've attached a video showing the issue, doesn't happen all the time but you can observe the popping noise as well as the hesitation during the actual blip.

[ame]http://youtu.be/Dcemc9U1yFg[/ame]