Worth it to upgrade manifold when adding a blower to stock motor??????

Go with a Holley or a Trick Flow. Can't go wrong with either.

EDIT: And it is EXTREMLY worthwhile to put a intake on a stock car, let alone a boosted one. The factory intake isn't worth it's weight in metal if you ask my opinion.
 
I don't know all the in and outs of an FMU.. My son runs a vortech with 42#'s and an fmu?? 525rwhp Anyway I think a custom chip and tune with 42#'s and you can get rid of the FMU. Don't know all the in and outs.

Steve