It Completely changed my GT4. It is now very exciting to drive. Better throttle response, and the sound is fantastic! I highly recommend doing this to your GT4. Next up my Speedster. Can't wait.

I installed the IPD Plenum and GT3 Throttle Body on my 981 Cayman. The installation was relatively straight forward and was certainly made easier by the use of a slightly longer bolt to pull up the intake clamps. (Once the clamps were pulled tight the original bolts could be reinstalled).
At the same time I also fitted aFe air filters and a Cobb Stage 1 tune. (On initial start-up the engine displayed an error code, the installation of the Cobb tune took care of that problem).
I was pretty sure that there was a performance improvement but the street is not really the place to test this out. However this was reinforced at the track this weekend. Previously the engine really didn't want to pull much over 6,000-6,500 revs, now if feels like it is continuing to produce all the way to the red line. The throttle response is also much more immediate. I am very impressed!
The Soul Exhaust and a Stage 2 Tune is coming soon so I am hoping for further improvements.

As one of the first new Cayman S owners ( American, living in England, USAF military) I made many modifications including an IPD plenum to the 3.4 engine which improved the overall performance and tractability . The Porsche is a "keeper" and the plenum performs faultlessly to this day!

Works well with the GT3 throttle body, headers, exhaust, and tune that I had on my car. Hasn’t and never will be on a dyno but feels quicker and that is all that counts in this 14 year old car.
Not being a mechanic the folks there were very helpful with instructing me through the process. Will re-evaluate doing the same to my ‘18 991.2 when it comes out of warranty.