Back now.

The first problem is that these bushes were not developed for the 928 they were developed for another vehicle and someone noticed that they sort of fit the 928.
So when they arrive without any fitting instructions and you phone up the supplier for advice they will be pretty clueless as to how to fit them

However, once I'd got the upper arms off the car and dismantled one and laid them out on the bench it became obvious which way round they should go.
You then face the second problem. - Although you can just about physically fit the bush with one lip into place its impossible to fit the other without an automotive press.
So unless you own an automotive press you will have to pay a visit your local friendly mechanic to get them pressed in, for a minimal charge.

The photo shows an S2 & S4 N/S/F upper arm and what way round the bushes should go. You will have to drill out the old bush (which is not a pleasant experience) and then knock out one of the threaded pins to remove the steel section. Make sure everything is cleaned up then re-paint or have the steel section re-plated in its original gold zinc + the washer and bolts.

The bushes themselves are very good quality and do the job - you just have the hassel of fitting them but you will save yourself about £1200+ on OPC costs.
Good luck.
