it will be weight reduction like they said f30 would be over e90. in other words you might see 50lb or less. dont get your hopes high.
on the other hand the new s55 will probably be just a fancy n54 with bigger turbo, more carbon build up inducing direction injection, water/air IC and underrated like n54. so 415 will probably put down 400whp.
garbage in garbage out. should have stick with n/a and keep turbo mumbo jumbo for 335.