Soooo...1000 miles later and this is what I have learned.
Most of my issue was the having new (deeper tread depth) tires on the rear and well worn tires on the front. The front would actually respond faster than the rear causing the twitchiness feeling. I quickly installed the front RE-11 265's.
This would be the case with or without matching brands of tire. Don't really have any experience mixing brands of new tires so I don't have an opinion on whether that is a bad idea.
Also, while we all know new tires have a release agent that must be worn off in the first few 100 miles, I was not thinking about how long it would take for the tires to match my alignment. This took almost 750 miles on my car (lots of highway miles).
Now after 1000 miles on all 4 tires I am once again in love with my Z
Thanks for all of your input
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09 370Z - FI TDX CBE/Stillen G3/FI HFC's are next
06 Xterra OR - 3" SL - 33" Pro-Comp MT's - Shrockworks Sliders & Rear Bumper/Tire Carrier - Stillen Cross Drilled Rotors/Pads