RCA's will be required if you lower the car by any significant amount but remember that the rear roll centre cannot be adjusted by very much so you are pretty much limited height wise by rear roll centre height.
I have spent years getting my tarmac rally car handling how I like it and that involved fitting everything that was recommended to me, taking it all off again and then re-fitting it all one thing at a time...
I'm now using 13" wheels with the panhard rod parallel to the ground for the rear ride height and the front is adjusted to suit.
190lb front and 160lb rear springs (AE86 diameter not coilover)
TRD standard length front inserts
TRD rear dampers
Standard AE86 sway bars front / rear
Prothane bushings throughout
Power steering knuckles.
It works really nicely, great balance but with plenty of grip. But that's just how I like it.......