The stock up is fine on your car, it is catless. they arnt good on 2002-2005 wrx.
keep the stock bov, hks bov is a piece of garbage. stock will work fine.
Have the tuner put on a 3port if you can afford it, it is a good upgrade.
you just need the turbo and an sti tmic. your internals are fine for a much bigger turbo than a vf.