One thing to consider about your 999 forks is that you will need to add a spacer to your caliper mounts, as the calipers on the 999 are farther apart than on a monster. Specifically, the rotor offset on the 999 15mm, the monster is 10mm. You need to move your calipers in 5mm on each side. Or the rotors out 5mm... Caliper spacer is easier & cheaper...
Now are you talking about needing caliper spacers using 999 forks and 999 calipers? or are the mounting holes for the calipers different on the 999 forks? I'm doing the 999 fork swap (courtesy of Theo
) and have calipers from a 2004 ST4s (65mm mounting, 2 pin 4 pot calipers) would that setup constitute a need for spacers? if so, where are you getting them?