I rock a WRX too.
When I had my off-the-shelf Vishnu tune, I was hitting full spool around 3500, but that was without a TBE (2 cats still bottling things up). Now that I've got my high-flow TBE and custom dyno tune from Shiv, I'm at full spool by 3000rpm. This damn TD04 is way small.
How are you planning to hit full spool by 2500rpm? And 18 psi? On what turbo?
I'm currently looking at a slightly used VF34, that's being sold with pinkies and a Walbro. Damn good price. I'm tired of my turbo running out of breath by 5000-ish rpm.
I'll be on the stocker, except its port, polished, and coated.
I plan on hitting full spool by 2500rpms, by...
Cobb AccessPORT + protune
Pnp + coated td04 turbo
Ebay TMIC (which is almost 100% going to be traded for a STi TMIC for less lag)
Pnp + coated + wrapped, helix flex uppipe
Pnp + coated + wrapped, perrin divorced wastegate catless 3in downpipe
MRT racing 3in axleback with 1 highflow cat in the midpipe
Pnp + coated stock headers with upgraded crosspipe that removes the tiny diameter flex joint in the stock crosspipe for a smooth ID throughout.
Pnp throttle body
Pnp intake manifold (hondata upgraded gasket to lower manifold temps)
Deleted + Pnp TGV (tumbler valves for emissions)
Go Fast Bits lightweight + underdriven crank and alternator pulleys
Silicone intercooler hoses
Grounding kit
Perrin electronic boost control solenoid (should help me reach target boosts sooner and hold them, should be especially helpful for the low gears where its hard to reach full target boost on the stock solenoid.)
17x8 Enkei RPF1's wrapped in BF Goodrich T/W 2's
I have brake upgrades as well and an eibach pro spring kit in the car. The pro spring kit will be out eventually in favor of Konis/D specs + prodrives, cusco/whiteline f+r swaybars and kartboy endlinks. That will complete my suspension and buildup for now.
Basically I'll be hitting that spoolup because all the port and polish work, along with the coating and wrapping of some crucial components to help with exhaust flow. I should be posting some of the best numbers for a stock turbo (without alcohol) in the country. Unabomber on NASIOC, the famous mod, made 242whp on UTEC and a lesser setup.
I might eventually go pnp + coated 16g, '06 wrx injectors (cheaper than pinks and flow more), and walboro pump.
My new roomie had a '04 WRX with a vf34 setup that was protuned and hit full boost by 3100rpms.