Poly bush difference really is like night and day, I deliberately ran mine for months without a rear arb so I could see if my theory was right, that the bush and the movement it allowed was causing MASSIVE toe changes, it was.
Prior to fitting the poly diff mount I ran no bar but std diff mount, the poly cut down on roll markedly by some 80% - 90%.
This was exactly what I wanted to know to confirm my thoughts, and it did, the car with a poly diff mount and no rear arb is still better by a mile than a arb equipped std bush car!!
I wanted to see how much the semi trailing setup made to toe changes with the beam going walkabout in every corner.
The suspension is a piece of crap for a performance car, with the squashy bushes, as I now call the std bush.
You do get a small amount of vibration, but more than made up for by all the other benefits of a poly over a std bush, I did not agree with the idea of solid beam bushes being the cure for the problem, I've since put poly back on the beam mount in plac eof my solids.
For suspension I always start at softest then up a click at a time, then around where I want stiffen/soften one end to balance the car grip wise, so just have a play.
I am glad 110% that I did a adjustable rear arb in 22mm, best thing I did was not listen to other people that had told me it doesn't work/won't work but none of which had ever tried it or driven a sapphy with it, it was made adjustable so I could soften/harden if needed, but with it brought a lot more comfort, it still has roll, not much at all at normal speeds but a little at silly speeds, as I don't want it too stiff and falling off the road, seems the ex F1 guy did know his stuff re suspension, when we discussed it.
A new beam entirely is being thought about presently, he just looked at std beam
and laughed, saying "that" goes round corners ha ha ha!!.
tabetha