[turtle]

First off, hello to all. Now to the theory:

This may or may not apply to the Boxster S (we own an 02)- but the symptoms and setup are the same.
I sell Nissans. The 350Z, one of which I own, was having the same issues with headers, exhaust, intake, and chips not adding much power, or worse, creating a net loss. The problem in the Z's anyways, was the knock sensor. As you increased airflow, the ECU sensed a leaner mix. Since the engine is set up out of the box to control emissions first, protect the engine second, and develop power last, the ECU would retard the engine, instead of dumping more fuel. The more stuff you did, the more it would pull it back. Even bigger injectors won't help. as the feul flow is control by the central ECU - same prob with new fuel maps. Sure the curve would call for more fuel - then old knock sensor pulls it right back.
The solution for the Z was to reflash the ECU disabling the knock sensor and the fail safe mode activator command, as well as a dummy plug that gave the MAF a constant intake temp reading of forty below.
I know that we are talking about two very different cars here - but both have vairable valve timing, MAF's, and knock sensors. These items work the same no matter what car they are in.
What do you guys think?
Has anyone tried this on a Boxster?
PS
had to repost - somehow or another I posted twice......then deleted the reply. sorry bout that.