Did all STIs have 6 speed transmissions? Or, were some equipped with 5 speeds?
I see. My feeling is that you may be simply improving parts availability by going to a Subaru gearbox, not reliability ultimately. The stoutest WRX gearboxes with 5 speeds are reportedly the v5 and v6 STi RA units but you would be dealing with an AWD gearbox that would need some work to suit your purposes, and I honestly don't know how strong the high gears really are in those.Kennedy Engineering makes the adapter to fit the two together.
I have been using a 901 trans with the 2.5l Subie for the last 2 years. It has a pump, cooler, and 3 oiling points for the gears and pinion.
The problem is it shears off 4th gear from the torque and the replacement gears are hard to find. The 915 and 930 gear boxes have the same problem with replacement gears.
Considerably, yes. The question is, though, will the gears stand up to racing, sticky tires, and constant strain due to excessive power? He's trading one kind of stress (AWD), for another (power, racing), so I still don't see the gears lasting very long.My personal thought is... there will be quite a bit less stress on the gears when you go to 2wd.