Not entirley sure for the 987, but on the 986..
std factory unit used the internal amp of the headunit - which means easy hook up of anything aftermarket -coupled to simple paper cone one way 4" units in the dash top
porsche sound package (PSP) gave a separate amp in the front boot, wired to the headunit by fibre optics, and uprated speakers, albeit still paper cone Nokia untis ( in dash were 0.75" tweeters, 4" midrange) and then 5.25" bass units in an enclosure in each door
Bose - uprated Bose manufactured speakers, with interior noise sensor, plus subwoofer betwene seats. amp in fornt boot still
I don't expect the 987 to be much different - the headunit is now double din sized (twice the height of standard) but the connections on the back are the same as the CDR23 of the later 986s.
PSP is not the last word in hifi but its a safe option for resale and suits 90% of buyers. Bose might be better, but its an acquired taste and a softtop is not conducive with acurate sound reproduction anyway.
Of course, after all that, for the first few months you'll only be listening to the exhaust note [
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