The Perrin for the 02-07 crowd will be hard to get new. Its discontinued. The TurboXS, APS, Spearco, or a quality larger than STI aftermarket TMIC will be fine. But, if your going to put it on. You should be planning on tuning it at some point or it's worthless to put it on. You'll probably get a CEL at some point. If you don't get it protuned at some point. Cobb has the Access tuner race beta. But, I'm not that familar with it and how to correct a stage 2 map to include a larger than oem TMIC.
378awhp/373wtq Custom Dom 3 & CBRD tuned 2006 STI.
"When in doubt...flat out" - Colin McRae