I put infinity speakers throughout my XK. it is the single most impactful upgrade I have done to date. I am absolutely in love with the sound quality. Here are the part numbers.

Infinity Reference 6032cf 6.5-Inch
Infinity Reference 3032cf 3.5-Inch
Infinity Reference 9632cf 6x9-Inch

A few install notes. The 3.5"s are taller then the BAs I had, so the plastic grill is bowed up a little, but not too bad. Also, I had to drill new holes for the 6.5"s. The factory holes where too far apart for the infinitys. It wasn't a huge to do though, all in all, a pretty easy upgrade.