I've been with the Hybrid setup for almost 2 weeks. Broke in the motor in a week and just got dyno tuned. here is what i did with my setup.
This is what my tuner recommended:
OEM STI short block
Machine 0.2L WRX heads
ARP Head studs
PE Timing belt
NGK Iridium plugs (one step colder)
New STi Gaskets
STi oilpump (I upgraded to the cosworth pump)
Overhaul gasket kit (since everything was open)
Invidia Up & Divorced down pipes
Apexi Noir catback.
Act Clutch Disk
lukasandrew is right in saying your engine bay temp will rise. But i havent seen an issue with it yet and it has been in the 100s lately. I imagine you would have no kind of issue since your in WA.
I would suggest dumping the headers and going with a bigger cams durations. You'll have more gains with cams. When setting up the hybrid it will fall short fast in the top end because of the restricted flow. You can combat it with a bigger turbo, but you'll have a way better top end if you had a better cam profile with a bigger turbo.
I was on a budget and didn't have enough for cams or a turbo/injectors/fuel pump/TMIC so i'll be doing that down the line after suspension and tranny work. But the TD04 is pretty much a pea shooter with the 2.5L block, but since your engine is open, you might as well work on the internals then focus on bolt-ons later.
Just my .02