what is all needed to give the 2.5i an LSD...i know the front/rear are 3.90 and the center is a 1:1...i also know i need to look for a R160 rear end...but what I am confused about is i can't seem to find a r160 in a 3.90...i know the WRX is a 3.54 and people say i should just swap out the ring and pinion but where do i get a 3.90 ring and pinion to even swap lol...

also will my stock axles still work or will i need to swap those out as well...

 

as far as your axles are concerned you will have to change em to fit an lsd on a normal diff both c/v's are the same. On the lsd however they are different on either side. with your diff ratios only turbo models came with an lsd and they also have completly different ratios to non turbo models so in short if you want tha lsd and you cant find a 3.90 ring then ur gonna have to change the gearbox 2 :-( its not all bad the ratios from turbo models are much taller neways so unless your building a drag car both a box and diff is a better option i myself had to change my g/box from a duel range to a single because i couldn't get an lsd with the same ratio. so i bought a half cut instead of a stand alone motor now my 90 model liberty/legacy wagon has a ej20 twin-turbo motor ecu and driveline and sporting a ball tearing 215kw at the wheels with all the standard induction piping so on that note keep messin with it and u will get there

 

well the WRX rear LSD is a 3.54 because it runs a 1:1.1 ratio...the STi is a 3.90 cause it's a 1:1 like the 2.5i...and i know the rear WRX r160 diff will fit on the 2.5i...my question is if i can just swap the ring/pinion from my open diff into the lsd from the wrx or if i have to find an old school RS r160 diff and take it's ring/pinion combo...

and after further research i know my axles will work with the WRX read end...it uses the same rods and connections...it's the internals that matter...(esp since the rear LSD in a wrx can fit into the pumpkin on the 2.5i)