Here are some pics of the diffuser.

 

Sounds like quite a deal for someone looking to do this. Although, it looks like the exhaust tips were made to fit a dual exhaust XK, rather than the quad tipped XKR.

 

Totally agree with kj

 

It is the F/X Designs package, which is the same as I installed on my car several years ago. The rear bumper, alone, was about $1800 so if it includes the front splitter and the exhaust tips, it is indeed a good buy. When I purchased mine, I didn't care for the front pieces nor the exhaust tips, and I already had the Mina front splitter and side skirts. I also replaced the black honeycombed plastic inserts in the rear diffuser with steel mesh (from Mina). It's a very nice looking rear bumper/diffuser and at $600 represents great value.

 

Most cars with ground effects looks awful...especially on a Jaguar. I vote that you leave it original. If you want to change the look, then consider new springs and drop it down about an inch and put on some new rims & tires. It is fully reversible and won't kill the beautiful lines of the body.

 

Mine will be getting a wing, front splitter and canards and a rear difuser made from aluminum by me. I agree, most ground effect bad or overdone.