The differences in numbers (from a 1994 service manual, for those who like the nitty-gritty):
XFI Model
Standard camshaft lobe height is 39.628 to 39.788 mm
(1.5602 to 1.5665 inches).
Wear limit 39.528 (1.5562 inches).
Base and LSI Models
Standard camshaft lobe height is 40.415 to 40.575 mm
(1.5911 to 1.5974 inches).
Wear limit 40.315 mm (1.5872 inches).
International heart transplant: the Blackfly gets an XFi cam - MetroMPG.com