Just from what people have told me, the change of intake wont make any difference unless you plan on having your ECU remapped (Uprev i believe) as the ECU is adaptive it will simply alter the air intake to bring your bhp to its original setting.
The only thing you will achieve, especially with a pop charger, is some increase in noise. If you want the added bhp, best to do the other mods aswell like plenum spacer, exhaust, and pop charger then get the ECU remapped.