Too add to what he said, BPU (basic performance upgrades) are known to give the best hp/$ ratio. They are the Greddy BCC (highly recommended from what I've heard), exhaust, intake, bov, boost controller, and small things. Then there is BPU+ which is where you add things a big larger, I think Cam gears fall into this, and BPU++ is where you have everything except bigger turbos, fuel systems, and big things like that. In good conditions i've heard of just plain BPU supra's getting 380-410rwhp on a dyno, of course you lose some power going to the streets but that is nothing. if you google supra build there will be tutorials and/or guides that will help you get the highest hp/$ ratio while keeping your car practical (not running 22psi on stock turbos). Because you have a Jdm car the dicks turned the boost down, restricted with exhaust and stuff
unlike the usdm which start at 330hp, jdm start at 280, however with bpu upgrades both cars will be exactly the same, you will just notice a lot bigger change from jdm-bpu than usdm-bpu