Plazmaman Plenums are the best i have seen when looking to purchase a plenum. it works great and looks really good. They make em in some awesome 80tonne press.
go to www.gtr.com.au and have a look there (UAS) $1150
They are easy to install and use the stock throttle body (or you get another flange for any other type) and they use the standard gasket and runners.
Makes me engine bay look sweet and with the RB30DET i can fit my strut brace =)
They have been flow tested and proven to make power as well.
DYNO SHEET BELOW SHOWS RESULTS OF THIS PLAZMAMAN PLENUM & INTERCOOLER KIT FITTED TO A SKYLINE R33 GTS-T WITH STANDARD TURBO, STANDARD ECU (WITH FUEL CUT DEFENDER), STANDARD ENGINE INTERNALS, ADJUSTABLE EXHAUST CAM GEAR, RAM POD AND FULL 3" EXHAUST SYSTEM.