I have a 1999 XJ8. I found these suspension upgrade parts on ebay. They include a front upper strut tower bar, a front lower ladder support bar brace and a triangle rear lower tri tie bar arm brace.

Ultra Racing Rigid 1 PC Solid Front Upper Strut Tower Bar 97 03 Jaguar XJ 8 X308 | eBay

Ultra Racing Front Lower Ladder Support Bar Brace 97 03 Jaguar XJ 8 X308 V8 | eBay

Ultra Racing Triangle Rear Lower Tri Tie Bar Arm Brace 97 03 Jaguar XJ 8 X308 V8 | eBay

Does anyone have any experience with these upgrades? Do they make a significant difference in handling? Are they worth buying?
Thanks.

 

I am no expert on suspension tuning, but the X308 uses a double wishbone front suspension set up, not a Mcpherson strut set up like they show in their how it works cartoon. The so called strut brace only bolts to the damper mounts, the jag springs actually fit into the subframe. The same at the rear, the wishbones do not bolt to the chassis but to a subframe . IMHO its just bolting on extra weight.

 

^ this

I've seen them before. Some people on here (if you search) have said they tighten up the front end a bit, but only on XJ8's, as they won't clear the intercoolers on the R's.
Also, from what I can see in the rear, it's bracing something that's already a brace :s