-wheels/tires-wont void warranty
-any cosmetic exterior changes-wont void warranty
-cold air intake that does not require a tune (i cant see them voiding your warranty for this)
-suspension, they probably wont value your warranty if your struts/shocks go bad but theres no way they could void the warranty for powertrain or if like a window actuator fails.
By the way, they cant void your warranty if you just put the part on the car. Technically they have to prove that the part caused the problem. (yes there are variations of this and different circumstances, someone could easily just lie)
You really should just find a cool dealership near you because some are mod-friendly.
I have one by me and they basically said that anything short of a tune or Forced induction wont have an effect on the warranty.
2014 Black Mustang GT. 20" Amr wheels, Sr Performance lowering springs 1.5", stillen front chin, mmd window louvers, roush AB exhaust. FOLLOW ME ON INSTAGRAM: @barrios_Luis