The campy freehub was changed when they moved from 8sp to 9sp, and since the change the freehubs have been compatible with 9, 10, and 11sp cassettes. So you should have no problem if you have a 9sp cassette on there now.

Just make sure you have the correct lockring for your smallest cog....IIRC 11 tooth cogs use a different lockring than 12 and 13 tooth outer/smallest cogs.

-j