There was once a time when the WRX came with a rear limited slip differential. Glorious. Unfortunately the VA chassis WRX – at least in North America – comes with no mechanical locking diff. Instead they have a fairly primitive form of torque vectoring which leads to frustrating one tire fires.

As we added power to our development WRX we could either swap in the STI transmission, center and rear diff (which are all mechanically locking) … or … see how much a rear limited slip can help things out.

We went for the latter at a much lower price point and much simpler install and it certainly adds a lot of what was missing from the driving experience. The car is able to put down power (especially in sharp corners and on snow/ice) much more effectively and it is even able to power on oversteer! Yes! Subaru please bring back the LSD as an option for this car – we know Japan has it because that’s the LSD we got.

The unit we installed is a Torsen gear based differential that does not bind at low speeds and uses the OEM 75W90 fluid. The rest of the install we put in video form, so enjoy the the video below and give us a follow for more technical content.

Torque specs below because they are a bit hard to read in the video