Hi,
I've got an 05 WRX Blobeye as well.
As other people said in your original post, I followed Andy F's website for Stage 2A.
Got the Walbro fuel pump.
IIRC, you might just need the Samco hose from the intercooler? Someone else will correct me.
I've kept my Prodrive back box but got a Meercat sports cat with wider mouth downpipe, decatted Meercat up pipe and centre section. They would make theirs fit yours....if it isn't a standard size?
Got the Y piece when I replaced the TMIC with an Sti one... a bit safer I was told.
I then got 550cc injectors and a VF34 turbo before getting the remap.
Now I'm looking at 334bhp/335lb ft.
On top of that...I also got the STi8 bonnet scoop (the big one) with undertray to get the best out of the TMIC.