Looking at the link from lopalong, I guess integramod is a premodded based on phpbb 2.0.23, as Icy Phoenix.
Due to have the DB the most optimized (that way you will have no rows on the DB that will never be queried), the best way to update to Icy is cleaning the DB first to a vanila, mod clean, phpbb2.0.23.
just look at http://www.icyphoenix.com/viewtopic...light=downgrade for a workaround in downgrading. I have no clue about it, I have not ever used it.
and about upgrade, the instructions for upgrading from vanila phpbb: