upgraded calipers?
 

i was wondering if the 4 piston toyota caliper swap works on the zx's.
plain and simple as that.

is it just too wide to not use a spacer?

Indeed. The Toyota caliper will hit the inside back of the rim before it sits flush on the rotor.

hrmm i wonder what else i can use

Does your Z suddenly have 439593490hp? A good set of ceramic pads & slotted / drilled rotors will do quite well too...

yea i installed a Mr Fusion home reactor in it last night