While I haven't heard of FabSpeed before, It would be quite impressive to get nearly 100 more hp without a displacement or compression change. DME change.. ok.. Headers and intake I could see getting some HP. DME reprogram sure (but, now, what kind of fuel will be require - 94? 98? octane?
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While the "S" motor may have been slightly compromised due to not wanting to hurt 911 sales of the same year that were rated at 296hp, but seriously, do you think the Porsche engineers left 100 "easy hp" on the table?
Perhaps a bit apples to orange, but "old school" 911 race motors of 3.2 liter, twin plug, high compression, headers etc. motors hardly put out 320-330hp, on race gas.
A 70K miles "S" motor is hardly in need of repair, unless you have tested for compression/leakdown or the thing burns oil at an alarming rate.