My XJR6 has green colour Bilstein shocks that need replacing. While I am at it I would like to improve the ride. Is there anything better than the original Bilsteins?

 

This from an old Bilstein's catalogue so you have an original number to work from

Your XJR is on the very bottom and notice the harder B6 rating ( ? ) , first 24 number is the front then rear

Motorcarman had a suggestion on the front lower shock attach point bushing to be replaced ( does not come with shock ) You can see daylight through if you look , It would give a rattle on ride

He says there are substandard manufactures that do not last long

Xj 1995 - 1997 (from 720125 To 812255) (x300) Classic / Wishbone-upper And Lower | Jaguar Land Rover Classic Parts

This will be item 13 called Damper Bushing , Jaguar # CAC75851

Andy is offering a front sway bar link upgrade ​​as you already on the XJR have the larger diameter sway bar

There is on the rear the more solid X308 crossbar that can be and has many times substituted ( can be done without rear suspension removal and just " slipped in " ) there is a little hardware difference

See item 13 on this X308 , Bushed differential strut part # MNC3713AA for the softer bushing and MJA3713AD for the harder

Xj 1998 - 2003 (from 812317 To F59525) (x308) Classic / Wishbone Assembly | Jaguar Land Rover Classic Parts