Also why are you running a 52mm TB? I thought these plenums were set up for 58's??? You might also want to find a 52 from a 3.3 V6 (if you don't/can't change up to a 58) as they have the same vac ports as the Turbo's. The 52 with ports in the center bosses are ported vac, where the 52 with a port in the outside boss is true vacuum and the one in the center is ported. Not sure how the GTP is set up vac wise with the TB though.