I ended up picking up the TRD intake out of .... curiosity I guess. I also picked up a Cusco rear anti-sway bar.
Car background: Owned 2 WRX's and 3 Civic Si's with plenty of experience in modding and tunes.
I decided to purchase these parts after paying off my student loan and having some free cash leftover to play with "owed less than I thought." The TRD box does indeed have a different design compared to stock which I realized after looking at more pictures. In person, the box has a lot more volume within it and pushes closer to the engine, thus it has a much shorter hose connecting the box to the throttle body. The filter looks exactly like the k&n "k&n probably makes it." I already had a k&n and tried to just purchase the hose and top box for the TRD intake but no one is selling them separately yet, I emailed websites and dealers but it was a no go.
After a couple weeks with the intake here's what I notice: Butt dyno = no difference, I've always had a weak butt dyno lol. Throttle response is improved, the car is much more willing to jump to higher rpms, I'd say it's a cross between normal mode and sport now. Sound is actually quieter but at higher rpms the engine sound has a deeper note which is nice. Any actual power gains: Again it is not felt but I noticed while watching my rpms during my hilly commute that the car doesn't need to rev as high for 2 of the larger hills in cruise control to maintain speed. I make the same boring traffic free drive day after day which is why I don't have a sports car anymore, during these same 2 hills with cruise at 75mph the car now revs about 200rpm lower to maintain it's speed. Likewise with my same 2 daily on-ramps, half throttle would get me to about 70-72mph by the time I hit the hwy and that now gets me to about 74mph.
None of this is scientific, it's just "not" things I was looking for and happened to notice which have been consistent. When I installed the intake I also removed the charcoal filter. Install was easy except for the plastic nipple that you have to remove from the stock intake and insert into the TRD rubber hose. It was a pita to get out of the OEM and a challenge to insert, WD40 helped with the re-installation.
As for my Cusco rear anti-sway bar, installation wasn't bad, the only challenge is getting it out after it's loose and shoving the new one in it's place. Removal of a couple small bolts and push clips to drop the under plastics is necessary to reach 2 of the bolts. Installing these bars is always a knuckle buster but I can say this is the easiest I've ever done. Can't really review it yet since I put it in yesterday but during a short test drive on our terrible small town Oklahoma roads, I noticed the car doesn't wobble nearly as much with road imperfections but you do feel those imperfections more. My goal was to make it feel more stable on the hwy, I'll find out more on that when I go to work tomorrow.
Other mods I've done, full led replacements of fog, head, license plate and interior lights. Used Philips bulb / chips for almost everything. Straightened my off center steering wheel by adjusting the tie-rods without changing alignment. Even had dealer check alignment after "wanted it checked before installing the Cusco" and it's dead on, no surprise since I learned that trick a long time ago and have done it many times.
Future mods: Stereo replacement with underseat sub once someone does a DIY head unit install and verify everything works. I'd like to do the TRD springs but I can't afford to loose an inch of ground clearance, with heavy rain I used to have to use a different street to get to my house with my sports cars because of a bad dip that floods. Roads here are realllllly bad.