Well when the 06 came out, they had the highest flowing injector, not sure about the 08s. But what this did for Deatchwerks was make it easier for them to modify which was why the wanted them so bad and was willing to pay for them. Not sure why the lowered the return now.
As far as BOV/BPV goes you can run the Perrin unit, you will just have to take your whole IC splitter off, the rubber and the metal piece also. But knowing Im a Cobb fanatic, take this as you will, but if you can get ahold of the new Cobb XLE BOV, I would get it. Its much better constructed than the Perrin one (all solid metal), you dont need the stock BPV elbow, its easier to adjust spring tension (the Perrin one is overly simple, it would loosen by itself, the Cobb wont), the sound is much better. Im still working on getting a sound clip up. Im runnning mine in hybrid mode which sounds better than the Perrin one and I dont have any issues what so ever. When I purchased mine, a guy that worked at surgeline was running the TurboSmart hybrid BPV, he liked the Cobb on so much he took his old one off to run the Cobb unit.
As far as my setup (running the TurboXS TMIC), its a great match up, and Im not even limited by my IC yet. It maybe spools 300-400 slower than stock, but hits like an SOB. My tuner said its a great setup/match with still room to grow (but of course Im limited by the tranny right now). And my setup got me 330 AWHP (319 ft/lbs tq) on a mustang dyno.
Sorry for the long post, but wanted to be as thorough for you, being that I have ran both BPVs, and you are looking for a similar setup as me. If you have any more questions feel free to PM me.
"2007 WRX- PPG'd, 20G- Tim Bailey tuned
Stage 2 2005 WRX