hey mate if its a 1996-2000 its a 3sgte engine st19 i think but def on the 3sgte engine as for mods a boost controller is a definate i paid $75 nz for mine installed very easily from trade me also a blow off valve the factory one is ok but just not noisy enough king spring lowering springs depending on how much money you want to spend on the car maybe front mount the intercooler (VERY EXPENSIVE) i think that thats really all the caldina GTT's need they are VERY FAST CARS 14 second 1/4 mile i have been told. My boost controller is a Go Fast Bits Manual Boost Controller works very well but with a boost controller i DEFINATLY recommend you get a boost guage aswell as to not destroy the turbo with to much boost even if you don't install the guage and just hook it up to set the boost anyways good luck with it mate cheers.