Well this winter my project is to turn my Forester in to (as close as possible) a JDM Forester STI. My first step, logically, will be to swap a 6MT from a USDM STI in to it, I'd go with a JDM 6MT but the swap is a bit more complicated and gear ratios are a bit of a grey area!

Things I need:


1. USDM STI Transmission (04-06, don't want an 07, I'll explain later)
2. Reuse stock clutch (already upgraded slightly) or use OEM clutch included with trans
3. OEM STI shift linkage

Mounting Hardware:
1. OEM or Group N 6MT transmission mount (different from 5MT)
2. STI rear subframe and diff carrier*


1. Driveshaft from an automatic Forester or Impreza (will upgrade to 1 piece eventually)
2a. Reuse stock rear diff (R160) with 3.9 or 3.54 Ring and Pinion gears (dependent on which year trans is used) retain stock axles/hubs/brakes/suspension in rear
2b. Upgrade to matching R180 STI rear differential* also must use STI rear axles, brakes, and hubs
2c. Suberdave R180 conversion (modifies rear axles to mount in to R180, retaining stock hubs/brakes/suspension)
3. Reuse stock front axles (for now) as well as hubs

DCCD Controller:
1. mapDCCD (I want it.)


Now, the reason I want an 04-06 and not a 2007 transmission is because Rallispec makes an affordable, stronger gearset. Which also happens to have taller ratios from 2 to 6 which I want really badly. 60MPH at 2000RPM in a Subaru is unheard of, so I want it. There are two main reasons I want this swap, one being the STI trans is much stronger than the 5MT, and two, I really would like as close to a Forester STI as I can get, it's unique, practical, and fun! I've calculated all the parts to cost between 3000-4000 depending on what I use and reuse and where I can get it, which is totally ok with me, also the way I am doing the swap (just trans essentially) allows me to convert the rest of the drive train to STI parts when ever I find the money or time (I.e STI brembo brakes, 5x114.3 hubs, axles, differentials, driveshaft, and suspension).

Stock Forester information:
R160 rear differential
4.44 Final drive (unusable with any STI trans)

Crazy short gear ratios (60mph is at 2600 RPM in 5th)
Weak, holds maybe 300WHP reliably

STI Upgrade information:
Stronger than R160, good for 500HP maybe?
Heavy, like 20 pounds heavier than R160
Requires STI rear diff carrier (bolts in to Forester so no problem)
Requires R180 axles (which require STI Hubs, which require STI brakes, which require 5x114 wheels) OR conversion kit from Suberdave for 180 bucks

Lower highway RPMS! (depends on trans, again)