Just wanted to close this thread out.

Installed a different manifold, and I opted to go with Fel-Pro Gasket, Dry. Noise is gone.

I still have a slight, small leak at the headpipe, but as I said, I found a small hole in the weld at the headpipe flange. The "noise" is 90-95% gone, thus I can start worrying about something else now. Thanks to everyone who chimed in.