Does anyone have any experience with the Polybush polyurethane suspension bush kits as supplied by SNG Barrret, or any other brand of poly bush available for XJ6 S1?
I have heard that some poly bush kits can have detrimental effects on the ride quality.

 

The only places I have used Poly in any of my Jags are:

Front upper inner wishbone.
Sway bar "D mounts.
Steering rack

Everything else was always Metalstick, as OE spec.

 

Grant has the right idea but I would add...

sway bar end links too
small bush in the rear trailing arm

These 5 bushes will increase the precision of Jag in a good way and add minimal harshness.

The upper front control arms and rack bushes will increase the road signal through the steering wheel.
The sway-bar bushes dont accomplish much unless the existings are perished and clunking but they will last much longer.
The small rear trailing arm bush is often broken and loose and replacement is problematic, the free moving Euathane version will increase control and last much longer while adding no harshness becasue the large bush soaks it up.

All other bushes should be OE style rubber for smoothness unless you looking for a modern precision sports car with modern high performance tires and all the harshness that comes along with it.

 

Installing my second set of urethane bushings in the lower control arms of my XJ12L. The first set went four summers, barely. mileage guess would be less than 5000 miles. Short life contributors, IMHO, larger than stock tires, and three hours of track time at Mid-Ohio.
Trying Energy Suspension bushings this time. We, the neighbor with a lathe, and myself, will have to modify theirs to fit.

 

I installed poly bushings in the front lower control arms. A) What a miserable job. B) Yes, it definitely increased feedback and harshness. There is probably a better way (as discussed above) to get more precision handling. I also have poly steering rack bushings.