the reasons being is that the boost jets that come with the jwt chip will only give you boost of between 12.5-14psi when the jwt chip will safely handle 14.5-15psi ( thus more power..15-25hp more ) plus the boost controller will allow faster spool up and more precise boost control ( no spikes ). also consider gutting your pre-cats for additional rwhp and also faster turbo spoolup. And set aside ~600$ to upgrade brakes ( rotors/lines/pads/fluid)..your really gonna need 'em!
1990 Twin Turbo 5spd Stage "Stock+" No Show,All GO 1999 Maxima SE 5spd ..also performance modded