On an 05 I did:
From http://www.subarugenuineparts.com/
STi Air Splitter 2004-2005 $69.95
STi Scoop Duct / Bellows 2004 $29.75
STi Hood Scoop - 2004-2005 Model Painted to Match $190.00
Plus $1.50 EACH for 17 of the little plastic clips for the bellows
and $2.50 for some 1/8" weather stripping(the stock splitter had some on it, and the new one didn't, so i just replicated it.

And from http://www.hosetechniques.com/catalo...Gloss%20Finish
50.275-300-110 $10.50 (2.75" ID, 3" long)
56.200-418-110 $38.25 (2" ID, leg are 4.18" from center of bend)
I also got the suggested T-bolt clamps.

Used 04 USDM STi TMIC with Cast Y.

Bolted in with no trouble. I put the bolts in finger tight and looked at the alignment of the TB and it was great. With it bolted up I used a set of $5 calipers to see what length I needed and cut the TB hose with a razor knife(if you've never cut silicon before, it helps to wet the blade, spit works great). The 90° hose was a little more tricky. I put it on the IC, realized the top leg was too long because with it touching the turbo the IC was too far back, I couldn't think of a way to make an accurate measurement so I took the IC back off and made a carboard cutout of the hose. I put the IC back in and slid the carboard in and marked off what looked right. I cut leaving a little extra and tried to put it in, both sides still too long, so I cut exactly what I had marked on the cardboard and it went in. The only thing I'd note is the Y pipe is a little lower than the outlet of a PE1820, so I had to pull up on the hose a little to get it lined up all the way..

I did have to bend the AC lines just a smidge, when I goosed the gas the IC was getting a little too close for my liking, it didn't touch, but I didn't like it.

All in all it took me about an hour and a half.

I also have to give a BIG thumbs up to the folks at Hose Techniques. They were so nice and friendly. I blabbed with the owner for about 10 minutes because the ordering lady was talking to a race event coordinator. The hoses were absolutely top notch, no burrs, just as smooth as can be. The T-Bolt clamps were great too(they make their own), the only thing I'd note with them is the TB side of the TB hose is a little narrow, and the clamp looked a little wide, I hope it holds, the other 3 fit great. I had the hoses and T-bolts on order for over a week from Mach V and got the never ending "we expect them in a few days" I called hose techniques which is in So-Cal and manufactured in So-Cal, they had my box in the mail an hour later and I got them first thing the next morning.