VAP rotors and Porterfield R4-S pads fitted on XJR575 or any XJ with same size brakes confirmed.
I wasn't able to find where anyone had tried this and their site doesn't list them for the XJ.
After a few emails with Scott over at VAP it was decided.

I would say braking is much improved with this setup, much smoother than stock.

Front




Rear

 

Nice - and the best tire for the XJ daily driver too.
I fitted a standard set of Powerstop rotors on front of my wife's XJ, not slotted, but very good for my wife's daily driver.
I did look around for slotted when I was shopping for them but for our demands, not really necessary - more just for my personal preference.
Our XJ is getting a new set of the Pilot Sport 4 AS's put on tomorrow.
The old set are still sure-footed & performing fine, but after 4 years & about 30k miles, time for a new set.

 

Nice install. Are you getting the upgraded calipers in the future?
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Thanks, it took me a few years to learn about the All Season 4. My previous tire of choice was the Pilot Sport 4S.
In my opinion, I see no reason to put a max summer on any XJ. They wear way too fast especially the rear and after driving on the AS4.
I'll never do it again.

 

Thanks, I have no plans on upgrading the calipers, I looked into it and really can't justify the need.
I would need to see side/by/side comparisons and data showing bigger calipers are so much better on the XJ.