Who do people use for the tuning of their XFR-S? I've got a spires set of pipes in the back of mine, but want to consider lowering the car also,

 

Try VelocityAP. I did the Velocity AP ECU tune on the XE and am very happy. Easily self loaded with their package. They may have a pulley upgrade for you too....

XF and XFR

There is also Paramount Performance closer to where you live.

https://www.paramount-performance.com/Jaguar/

Hope this helps!

 

Oh man, I've been looking to lower my xfrs as well. I can only find spires coilovers which costs a pretty penny considering im from canada. They also mentioned that the lowering springs they sell will work with our cars and still have the adaptive dynamics still functional, however, the spring rate will not change and they advise against that.

I've also tried asking a company that puts custom adjustable collars on stock struts to make them like an adjustable coilover, but they dont have a collar designed for us.

Gsrmotorsport worked on a 2012 xfr creating a custom coilover by using the stock billstein struts but sadly i dont think they are in business anymore.

If you find a company that can do it for a better price, let me know!

 

I'd be a little gun-shy of doing a tune on the RS as it *seems* that the tunes described on here by most are simply copies of existing tunes Jag has on other cars. And those tunes are all on non RS cars... Without hard-evidence I would be leery of a claim of more power on the RS.
Over on the "F" forum there are a few guys who have managed to squeak out more power with tunes on their R which has the same engine. One in particular used a company who seemed to have cracked the transmission control unit which limits the input torque by feeding back data to the ECU. Check out his posts and perhaps you can mine some good data from who he used.
In theory, a pulley swap and exhaust upgrade would make a few more ponies. You'd be the first on here with real data on an RS if you do it.