bigger injectors (will be hard to find for a 4age as it uses side feeds), safc, fpr, a turbo, a manifold, downpipe, oil feed line, oil return line, a bov, a wastegate if the turbo isnt internally gated, a boost controller if u want to rise the boost above stock wastegate pressure, a bigger fuel pump is recomended, some cold heat range plugs, charge pipes, and a intercooler. and there should also be a boost guage.
those are the few things from the top of my head...
btw i would also recomend a nice aftermarket metal headgasket for the 4age..along with some ARP headstuds...as ive seen headlifting issues with a boosted 4age..
peace