Not to rekindle this tired old debate.. but I'm dropping this here (first post!), an overlay of the 2004 Boxster Base (2.7L) and 2004 Boxster S (3.2L) dyno charts.. as eyeballed from Porsche's own plot in the Owners Manual:
I was surprised such a chart didn't already exist, but maybe I just didn't search deep enough. Anyway, hopefully a helpful visual aid in the spirit of qualitative comparison. The raw numbers here are not very precise, obviously.
Picture's worth a thousand words, but here are a couple observations: If you can't feel the difference the extra bore makes, you're not paying attention.. at least 10% more torque everywhere, widening to nearly 20% more around 5000 RPM. That being said, if you're not living in the top third of your S model's rev range, you're really no faster than a Base model driver who's happy to make extra downshifts and flirt with the redline.