08+ oem wrx/sti sway bars will fit. If your on a budget get any 08+ sti rear sway bar, I believe it is 19mm. I have the rallitek swaybar kit: includes 22mm front sway bar w/bushings, 19mm rear sway bar w/ bushings, endlinks, bolts, etc. Just keep an eye out and you can find a deal on the classifieds here and nasioc.
Rear WRX Sway bracket Part Numbers for 2.5i Owners
I'm sure there is a 2.5i impreza owner out there besides me that needs these part numbers.
I'm 99% sure these are the correct part numbers, but please check before ordering Happy Modding!
Aftermarket sways will come with new bushings (and you'll probably want to buy upgraded endlinks as well.) So you'll just need 2 brackets and 4 bolts.
Bracket: 20466FG000 (you'll need 2)
Bolts for brackets: 010108200 (you'll need 4)
If you get perrin endlinks or whiteline endlinks, you should get new bolts from perrin or whiteline to affix them to the bar and suspension arm...If you get rallitek endlinks or another type of OEM style endlink, you'll need to use the OEM bottom bolt and nut.
Bottom nut for endlink: 902350001 (you'll need 2)
Bottom bolt for endlink: 901000221 (you'll need 2)
The above 4 part numbers I pulled directly from the part bags...so I know they are correct. The below I have not "checked."
Just in case you want to go stock WRX rear sway assembly, here is some other info:
Nut to hold endlink to sway bar: 902370046 (you'll need 2)
Stock Bushings: 20464FG000 (you'll need two)
Rear endlinks: 20470FG000 (need 2)
Stock WRX rear sway: 20541FG000 (just one, of course)
In your opinion do you feel like the 19mm OEM STI rear swaybars are a good purchase as a beginner mod? Sorry I'm completely new to everything haha.
If your a stock 2.5i, with no sway mods, Yes, IMHO, the 19mm OEM STI rear sway bar is a very good purchase.
One of my first mods was a WRX 16mm Rear swaybar and it was a great purchase. Would I have gotten the STI one if there was one at the time? Yes. the 16mm does make the 2.5i handle like a whole different car, but there was still lots of body roll, where the 19mm would've been a better purchase.