I have a 02 WRX with 06 STI swap. Initially when the swap was done, I can't really remember if the dealership ring & pinion or changed the hub that mounts to the drive shaft on my r160 to make it compatible with the 06 STI's 6spd. Now I am upgrading to a 07 STI transmission, and here's where the confusion starts. 1. What modifications need to be done with stock WRX diff for it to be compatible with 07 STI Transmission & drive shaft? 2. Will my r160 in current state will work fine with 07 STI trans? 06 & 07 STI Trans both seem to have same center diff ratios of 1:1.1 with 3.54 rear diff ratio. 3. Possible to run rear diff with 3.90 ratio on 06-07 STI, which had a rear diff ratio of 3.54? Some one who has done 07STI swap in their wrx, while keeping R160, please shed some light on these confusion. This is the info i got from searching around. Then i found this on dirtyimpreza.com: I have put 30k miles on my 06 swap, and it's running like a champ. Does anyone have Will's (WJM) number? He did my swap, he might remember what he did to my diff?
I am going to go call the dealership tomorrow with both trans part numbers and get specs. So far what i have been reading other than 3/4 gears. The center diff and rear diff ratios are same between 06 & 07 STI. At the same time I have been told 07 uses different center diff ratios. *scratching head*.