It does add power to a N/A SVT, and it helps to run lower PSI to reach 300-350HP max for stock internals, with a fast spooling turbo. Our stock intake manifold is restrictive, very for an actual built NA focus. Nothing is needed for our cars, but they're performance and this allows for more of that.
Seeing how the OP spent half the money of the manifold on a 69mmTB that would show less gains. The manifold woud be alot more useful then the TB.
Buy mine that is for sell FWIW.