Do a search you lazy flamin mongrel, its been covered so many times!
SITC to some degree? I disagree. To get the most out of your SAFC you need an SITC to add in or pull out timing as when you bend the fuel curve it also has a affect on the timing. Eg. Leaning of the air flow with advance timing (negative relation ship between the two)
Also coil packs are only going to affect it if the oem nissan ones are shagged.
Basically you want:
Easily breathing car (intake and zhorst)
Good spark (plugs and working coils)
Functioning O2 sensor
Clean fuel filter
some way to tune it all (sitc safc nisstune ect)