To reiterate an observation I made when this issue came up a long while ago, I would not use polys where there was any direct connection with Alloy transmission assemblies.The main issue with the standard bushes isnt the material they are made from but that they are void bushes which allow too much movement so with the alignment set correctly or even to a revised setting as soon as the wheel is under braking or acceleration load it moves rearwards and gives a lot more toe out.
This has been discussed many times and although oe is correct in his theory that is assuming that the design and development of these bushes was without error, and we all know that many other parts of the cars had design faults so it is fair to assume that so the bushes may not be correct.
Its a simple case of the poly or plastic whatever you want to call them bushes do improve on a bad design and without any reported downsides.
But there is a complete disconnect with the Q4 rear trailing arms and there is very little travel to exacerbate squeeks, in my experience.
The rear drive system becomes incredibly more precise, which with the four wheel drive system, leads to a much more predictable steering geometry. That was not the case hitherto. Accepted, one was leaking oil.
However, I did replace that arm with a new one at over four hundred quid. And while Powerflex developed the bushes I was continuing to "Play" with my 159".
I had them fitted within a few days of Powerflex contacting me, despite the back end being "up to spec", with the original arms. And the difference was immediately tangible. No squirming when I floored it and braking was also that much more precise. One could concentrate on setting the car up better for a bend, knowing the back end was precisely planted and no counter - adjustments were needed on the steering.
As for squeek, I just don't recognise what is being suggested. The travel is far too small to generate it - IMHO - less than 15 deg. The bushes are very large and any noise there may be would be muted. Assuming they were fitted correctly - tightened up with the car on the ground.
Nope - I remain unconvinced as to the argument about these bushes and they will work equally well on front wheel drive versions. Probably better as they are not subject to the same load as those fitted to the Q4. After all, they are substantially for location and they are much more precise than the standard ones.