I installed an Agency Power Race Plenum and Throttle Body from Dan of Vividracing.com in my 996TT. Acceleration response and power has increased dramatically. I have AP diverter valves, K&N filters, AP exhaust and Softronic ECU tune, all from Vividracing. The 996TT is now an awesome beast. After installing it, Ive been getting a CEL and the durametric state P1109 input variable charge measurement. Erased the codes but it kept coming back. I cleanded the MAF with contact cleaner and the K&N filters, yet, the CEL keeps coming back.

Dan sent me an email and said said a check valve must be installed at the new plenum as it does not have a built-in check valve like the stock unit. I discovered my Porsche technician didn't or forgot to install the check valve and just kept it in the tool box. I found the check valve and hose the other day and had it installed. After installing the check valve, the CEL never came back and the 996TT runs lie a monster. Thank you Dan.

The AP Plenum and TB is, indeed, an excellent investment for more power on the 996TT.

 

you felt a change from that mod alone?

There are many 800+ HP cars on here all with stock plenums so your comments are surprising.

 

I have the 74mm IPD Plenum and 75mm TB with K24/18, did not feel a bit of a difference.