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I have not but others here have done similar installs. If it were my car I would get a custom reflash with a dyno or a rolling tune and shoot for a big fat torque curve rather than peak hp. We buy hp but we win races with torque. More effective than off the shelf "chip" reflashes.

Some pitfalls others have faced with aftermarket header/cat/exhaust so just a friendly heads up:

Serious droning resonance at 3k rpm
Continuous CEL issues.
Cannot pass state smog inspections (not street legal)
Headers made contact with nearby PS lines, car caught fire and burned to the ground (yes, several Boxsters have gone car-b-que after installing headers)

Pay attention to the details.