Originally Posted by unclemat
Stock R160 is not Torsen, but viscous. Least desirable option.
As far as Torsen being better than clutch type - negative. Depends on the application. For road course in many cases - yup (and obviously for rallying). For autox and general street application - Torsen is a better choice. I guess it also depends on the driver's preference.
Also the stock 04-06 STI clutch diff (made by Hitachi) is crap. 2-way, very weak and with poor ramp up.
I was referring to the torsen being in the back of the spec B vs clutch in the R180 from an STi...only clutch R160's that I know of were the early STi RA's before they switched to R180's in Ver 4 IIRC...
clutch > torsen would mean that the clutch style is better than torsen...however out back a clutch will not go to open when lifting a rear inside tire nor allow wheel spin as easily. Heck even with some high powered Impreza's on stock R180's they are peg legging (spinning a rear wheel) coming off of corners BUT you already explained about those junk Hitachi units.
My vote for setup for most everyone, except rally, is a torsen/helical front and a clutch rear. Center's are very much a personal preference type of deal. A 1-way clutch isn't bad up front for tarmac but is noisy.