First take that 3.25 off and put a 3.4 in it'* place. Get rockers for some more top end. If you want to run the 3.25, you'll probably need a cam and headers. Ofcourse an intercooler is the best way to start and then go from there. Main thing is to get a scan tool so you can keep an eye on what'* going on with your motor. All cars react differently. I had rockers, headers and still couldn't run a 3.25 on my GTP. I also had 5*KR with those mods and a 3.4. Now on my Bonnie I run the 3.4 with just the minimal mods and see about 2-3*KR max.......every car is different.
2003 Granite Metallic SSEI 14.5@96
3.5 pulley, Intense PCM, 180 stat, Autolite 104'*, Intense FWI, Borlas, custom Y and chrome Tips, Aeroforce Scan Gauge, MBQuart HU, 12" Power Acoustic Sub, XM Roady XT, Silverstars
(former GTP owner)