no. a forged rotating assembly just replaces the stock components with stronger ones. the weak link in our engines is the rods/ pistons. the crank is good to around 600 hp. forged components are stronger, therefore can withstand the stresses of forced induction much better than the stock ones. forging the bottom end will not change your displacement unless you have the block bored. i had mine bored 0.020" over stock.
boring the block will change the displacement, but only a tiny bit. on my car, the change in displacement only netted something like 3 hp (yeah, i did the math). for a big change in displacement, you'd have to go with a stroker crank.