So I checked under the car and realized that there was a spot on the driver side where the header was touching the transmission bell housing barely! It's because I wrapped the headers and the wrap was taking up a little bit of space allowing them to gently touch. The exact same thing was happening on the passenger side by the subframe.
I cut the wrap off in those areas and use the prybar to slightly bend them out and then cleaned everything up and there's about an eighth of an inch gap or maybe a little bit more between those contact spots.
I then cut the hangers on the H pipe and realized that the tabs were loose on the passenger side rubber hanger holder. That's the rattling that I was hearing.
Then I realize the engine mounts weren't torqued down to 49 foot-pounds they were only about 10 foot pounds, so I read torque both nuts.
After all of this about 60-75% of the vibrations are gone. I suppose the remaining vibration I have is probably considered normal considering I have no cats and I have long tubes.
Definitely much much better.
