If it's not really about tuning or wiring. Then it belongs in here.
Currently running a seat Ibiza for track days however im looking to buy a gt86 in the summer
I don't have anything specific to the 86 platform, and I'm not sure what your current knowledge level is, but "Chassis Engineering" by Herb Adams is an excellent starting point.
This book is definitely a bit dated in some areas, but the principals he explains are still very relevant.
As a side note, I'm a big fan of the 86. They're extremely fun in the corners.
Milliken & milliken or Opitmim G stuff by Claude Rouelle