Sounds great. Might want to also think about beefing up the transmission a bit--external cooler and VB mod from climberD. Also, are you doing fuel mods as well with the 18g (injectors and fuel pump)? If not, you may want to stay a bit smaller with a 16g or VF52. Also replace your stock up pipe with a catless option (aftermarket or stock sti from 02+ will work just fine). And a downpipe, bellmouth design.
Hopefully you've already though of all of this or you just added about $2k to your build
And maybe new pistons...the stock ones suck.