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Fletcher -
good points. i think that in addition to the changes that you mentioned, the majority of the gains in the 987 have to do with RPM and nothing more. i think some revisions to the intake have allowed them to maintain good driveability in the low rev ranges while further expanding the top end's spark map / fuel map / variocam program to move the torqe peak further up the ladder.
if you look at the dyno curve on the previous page, all it would take is moving / extending the flat part of the torqe curve (190 lb-ft in that graph, blue curve) from 6000 RPM (peak HP of 217) to 6630 RPM and you now have 240HP. if you go to porsche's website, you will see that indeed, peak power now occurs at 6400 RPM. this isn't the full 6630 that we needed, so they have added 7 lb-ft of torque; easily realized with the larger throttle body and new headers.
i have LONG believed that they drastically underrate the rev limit capabilities of their cars. think about this: my 1986 toyota celica was a 2L 4-cylinder. it redlined at 6900 RPM. It did this with cylinders and valves that were LARGER than the boxster's (2.0L / 4-cyl = .5L / cyl vs. 2.7L / 6-cyl = .45L / cyl) and connecting rods that were longer. from a force perspective, the new box generates 33.33 ft-lb of torque per cylinder; the celica generated 31.25.
considering the fact that a) the inertial mass of the reciprocating parts weighed more and b) this was a massed produced TOYOTA and c) that was 1986; one gets to wondering why that would be.
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