[Timmay!]

Nanook,
Tough to get more power out of a 944 engine without major bucks.
BTW, the single biggest limiting factor in our engines is the AFM. It's basically a restrictor plate! Our engines don't need more fuel to make more power. They need more air.

Try a dyno pull.
Loosen the AFM.
Do another dyno pull while:
Pushing the barn door all the way open so the DME gets the right signal. Then remove the AFM from the system (still plugged in though) with the barn door being held open. The TPS should be sending the WOT signal to the DME. Let the engine suck in air through the 3" rubber J boot instead of the AFM. Watch the HP jump.

Be wary of chip claims. They're mostly exaggerated in my experience.
If you want to make your 924S quicker (not faster) drop some weight. We take about 300-400lbs out of a full 944 spec race car. Livens them right up!
If that's not enough, I also agree that you should just trade up for a 951.