there are compromises with each setup (SC, single turbo, twin turbo)... most of the BIG numbers i have seen have come from a big single
first off the dyno that is shown is the origonal dyno for single turbo and super charger. http://www.forcedairtech.com/turbokits_wrx_stage5.html i guess they lost their web guy cause they havent updated their sight in years. now onto the piping. it apears by air flow that the turbos suck in air push it into the sc then into the ic then to the throttlebody. http://forums.nasioc.com/forums/showthread.php?t=906159&highlight=twin+turbo+supercharged