yes they fit perfectly well i & i think many others use hitech 85mm filters in a cokin P holder.
they are of course 1 mm wider than cokin P filters and as a result they are very slightly tight in the holder ,nothing to worry about at all .
P.S
you'd of done better posting in talk equipment , no doubt had a reply before now.
[ edit ]
just in case you dont know formatt & hitech are 1 and the same