scratch the cam sprockets, its a pain in the ass to adjust them and the stg 3 cams are already optimized with the correct lobe separation angle for the 7k rpm range that you are going to run. For 500+hp you will need to run 11mm arp head studs and arp main studs. I would not try to do more then 400whp on a walbro just because making that much power is scary, not to mention on a 89 dollar fuel pump using stock 5\16ths line. You will have to get an after market fuel pressure regulator after changing the fuel rail. 550cc injectors will not do 350 whp at 43.5psi, try 320 with keeping injector duty cycle under 90%. Your turbo might do 425whp after that its a crap shoot. If you are looking at this much power I advise you get the .020" over pistons and have the block bored and honed so you start with strait cylinder walls, not ones with 100,000 miles on them. Ditch that fucking waste gate, ive seen too many cars with boost control problems with a deltagate, sc300, GN, supra, ka-t. You can get a 38mm tial gate that will bold up to the same flange on the turbonetics manifold, although I dont know if it will control boost with 500 horsepower worth of exhaust flow. You dont need a different intake manifold, although that and your 3in exhaust will be the most restrictive pieces in your puzzle.
Other then that its going to be the tuner and your AEM installation.
Another thing, you need to speak with someone who has done this kind of big horsepower setup before because they have the experience of knowing what works and what dose not. You need to think about your clutch options as well. Dont take anything you read here as law because alot of the opinions that I have read in this thread are not really putting you in the correct direction.
