In order of braking performance...
1) Upgrade stock S13 partsKeep stock calipersNew rotors (you implied yours were bad). I'd go with Brembo blanks.Better padsStainless steel linesBetter brake fluid
2) Q45/J30 brakes90-96 Q45 or J30 front calipers (theyre virtually identical)Q45/J30 front rotorsJ30 rear calipersJ30 vented rear rotors (90-96 Q rears are thinner and solid)Better padsStainless steel linesBetter fluid
3) Z32 brakesZ32 4 piston calipersZ32 front rotorsZ32 2 piston rear calipersZ32 rear rotorsZ32 drum style ebrakenew (longer) ebrake linespadslinesfluid
NopiOnline.com has great prices on Brembo blanks. See if one of our sponsors will match them.
http://www.SPLParts.com has lines for a great price: $45 per axles last I checked.
I say all this under the impression this is a daily driven street car, not a track car. Ducting wouldnt be necessary nor show much improvement.
Q brakes use the same sized rotors, with 'smaller' calipers. I'm pretty sure they will be as good as Z brakes, unless youre running some REALLY sticky tires. (but that isnt likely for a DD street car)