it is a possibility of some of the bolts backing themselves out because of the vibrations that aren't dampened by the stock mounts.  but it is also a possibiltiy that they will stay and you won't have any problems.  it just depends how tight everything is already.  when i built my motor is used blue locktight on a lot of the bolts because i knew i would have extra vibes from the rockstomper mounts, i havn't had any problems so far.