i bought my 1998 sti v about 4 weeks ago and managed to bid the price down from £12,000 to £10,500 because i thought the diff was gone (slight wine and some vibration)
so i bought a diff £500 had it fitted and it was the same, i then had the prop balanced £100 and the gearbox checked, still the same and no one seemed to have any advise.
I was starting to get pissed off with the car and thinking of selling it, so as a last resort i changed the diff carrier bushes on saturday from the power flex ones to standard subaru and the noise and vibration was gone.
its like a different car now and really nice to drive .
I thought i would mention glenburgie subaru breakers as well because the diff they sent me was not a lsd (the one i took out was) so i phoned them and they promised me that sti's did'nt come with an lsd (bull****) i had to fit it anyway because the car was in bits and i thought the old one was knackerd.
The old one with lsd is being fitted on friday.
cheers.

 

Cool, thanks - I was wondering whether the additional NVH on mine was a result of the new STi rear diff (that I fitted and aligned the crown wheel and pinion on ), the 6 speed gearbox or the Powerflex bushing which were all fitted together.

I kind of assumed it was the bushing, but it's nice to see confirmation. While it can get loud, the benefits far outweigh the drawbacks

Richard