Ok so here is what you do.
1 supposrting mods similar to your KAT
Maybe some headwork and a metal head gasket (HKS Apexi or Tomei with this one)
full exhaust
Z32 MAF
CAMS
Valve springs retainers
Rocker arm stoppers
2 fuel system
a -6 an lines from tank to rail
Good FPR not a nismo one
Big injectors throw the 550's in the trash get 740's or bigger or go home remeber any think over 850 are gonna low imedence and will need resistors
3 forced induction
2817r turbo or
3071/3076
4 Tuning and electrical
Buy a nice EMS Power FC is good but i can tell you with first hand experiance it is old and dated
AEM doent work well with the CAS without some modification
Get a haltech E8 or E11 or something similar
5 Suspension
Get all Power by MAX or SPL links
Get good coilovers Apexi, HKS, Stance, (Moton)
Get some good wheels where you can fit some decent tire maybe at least a 235 or 245 on a 9 1/2j
6 Profit