The presence of walmart in the thread make me wary. What brand are the disks?
The link wont work for me, but do you have a pic you can post?
Department store bikes, no offence i have two of them, arent usually worh upgrading, especially with a dual crown fork, or using it for downhill.
I found the bike on the walmart site. Its one of the *better* DS bikes ive seen. Its an interesing shock set up, for sure.
And maybe yo could try the Promax site for a manual/support on the disks?