A long long time ago far far away I had tested a plenum with the stock throttle body on my car with mods consisting of an exhaust and ECU flash as seen here. The plenum made torque and horsepower but lost up top. After retesting and reinstalling as well as questioning the issue, no further improvements could be had. Almost a year later I now have GT3076 turbos on my car and I want to continue to maximize the potential of the car and improve inefficiencies. I learned that the Porsche intake manifold system works off of engine pulses so the airflow pattern of the plenum is not important as improving the restriction of the airflow. You can only get as much airflow into a system as the smallest opening. So I took it old school…
For those older then me, you just bored out the throttle body. For those my age, we took our first tuner car and purchased one of those JG throttle bodies for more air. Wouldnt you know, it made a difference. The same is true for the Porsche 997 Turbo. The more air flow you can get it whether on the stock VTG turbos or on my GT3076 monster, the better performance you will get. So we went to work.
First thing needed here was a bigger throttle body. Imagine the cost to make one from scratch :(. So we spec’d the Cayenne TT throttle body which will work with the 997 Turbo drive by wire system. Because the Cayenne TT part comes in at 78mm, it will not bolt up to the stock plenum. This is where Agency Power comes into play. Our fabrication department had this CNC machined flange designed and built with a inner cut for a rubber o-ring. We then used aluminum tube the same size as the throttle body to make the T-Plenum. A straight piece of aluminum with fittings was welded to the back side of it to accomondate the factory hoses.
The factory part inlet is only 76mm which gives the overall surface area about a 3% increase which is quite alot of volume. Because of the increased air flow, we will be retuning the car to get a before and after dyno run. VRTuned is about to release a new product exclusively through Vivid Racing so you 997TT owners will not have to take your ECU out 
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Anyways stay tuned for the testing and leave your input.
