has anyone bought or tried to test fit these on the 08 xB??

Crutchfield says it fits but.....

http://www.crutchfield.com/S-z4K3wPat72x/cgi-bin/ProdView.asp?g=530&I=142SCXB04

that would be a no, unless they found awaya to keey the exact smake cardo space in the new xb as they did the old. i believe it only fits the 1st gen