Help with handling?

[Black Squirre]

I just got a 2014 almost new 1600 mile 370Z coupe, Im coming from a 2010 Roadster. Both cars have sports package 6mt. The roadster Was one of the best handling cars I had ever driven. Nice tight steering massive front end grip really confidence inspiring and Cornered really Flat. My 2015 is nice but much different not as Tight steering nowhere near the sure footed front end. The only difference is the tires My old car had Conti extreme contact the new one has the Potenza tires which look great but dont stick as well, With the bridgestones Im getting a ton shimmy and wag coming out of corners I have been leaving the VSC on (always off on the roadster). I think Im gonna put a set of Extreme contacts on the New car (285-35-19 rear and 255-35-19 front) Hoping that will help.

any other ideas?

Also I read vague posts about turning a bolt on the Steering box that will increase the tension on the steering. Anybody know about this?
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