usually making a baffle out of 1/2" mdf will do the trick, its pretty easy, You will need a jig saw. Trace the old 6*9 onto the peices, jig it and drill the holes where the screws held the speakers in place. then just simpliy trace and jig out the opening for the new speaker, usuality it is quiet a bit less then 6.5" -- I usuauly use silicon between the baffle and the bay, but that is optional.