Sorry i thought you said you had GTST, GTR requires no mods.
The pressure sensor allows you to map beyond the factory AFM, it also allows you to map the sensors then put this in a output map and take the airflow meters off completely (see explanation on page one) on GTR i reccomend running a nipple off each throttle body and then connecting them to a common tank to draw your map sensor signal. Our drift car ran this setup perfectly