Its been confirmed many times the sti sb is pnp. Read the threads from the start. Theres alot in em.
another performance upgrade that comes to mind is perrins crank pulley, also swapping premium fluids into the car. Tires also greatly affect performance.
if tires raise car 1/2" that means they are 1" wider than oem. That will affect your speedometer significantly. check tire calculators for exact numbers.