For some reason the engineers in Weissach decided that a "T" shaped plenum was the best for the newer 99x series cars (or maybe it was the accountants in Stuttgart). Unfortunately, this design leaves a few ponies on the table. BreitWerks is a dealer for the IPD Plenum which is a significant upgrade over the original Porsche design. Long story short, air would rather turn a smooth corner than an abrupt 90 degree angle. The average gain is 15hp/15tq. That's from just changing the shape of the tube that goes from your throttle body to your intake runner!!! The forced induction cars see even bigger gains. As far as we can tell, there is no downside to this mod. The aluminum construction does a much better job of maintaining a cooler charge air temperature also which means your computer will automatically adjust and give you better fuel mileage and more horsepower. Give us a call to find out what kind of benefits you can expect for your favorite Porsche!