A few simple, and relatively cost efficient mods you can run are a 3.4" pulley, headers, CAI/FWI, exhaust, and supporting mods.
It's a GT. So good stuff except the 3.4.
BUT after the paintjob done right you're looking at almost the cost of a GTP, so I'd just buy a gtp, maybe try and get like 500 out of that thing.