1. What are you running on the back?
the back is still standard s13 items, ideally you want 300zx items here, but they are hard to find, not to even mention the discs.. also im thinking that if you put 2 pot backs on, you will def. have to swap out your brake master cylinder too, the stock feels like it barely supplies enough fluid for 4 pots front and standard back. in fact that is the next thing on my list, a 300zx master cylinder.
Why did you go for cross drilled apposed to cross slotted rotors?
this was purely for cosmetic purposes, i doubt it does much for braking as modern pads supposedly does not gas out much. cross-drilling actually weakens the disc and under extreme use cracks might develop. do not confuse cross-DRILLED discs with those say for instance on the new m3's or z4's , those discs are CAST with the holes in, which makes a big differance to relieving stresses and cracking. that said, bmw obviously believe there is something to be gained from crossdrilled disc,they put them on their performance cars.. slotted discs are fine, but they will half your pad life..
you mentioned in your original post that the old shape elantra ran the same breaks as the s13, is this true for the rear brakes as well?
nope, just the fronts are the same as far as i know..
having driven with this setup for a while now, i have not felt any brake bias problems, it just feels sometimes as if there is not enough pedal stroke.. thus i want to fit a bigger master cylinder.. otherwise it feels fine.