I have a 2009 Cayman with the Sound Package Plus. I never liked the sound so I replaced the head unit and the difference is HUGE. My replacement unit was inexpensive (
https://www.cnet.com/products/pioneer-fh-x731bt-car-cd-receiver-in-dash-unit-double-din/
) and has lots of features including control of most features/adjustments from my iPhone. You have to purchase a harness and housing separately (
https://www.suncoastparts.com/product/OEMRADDELE.html
). The problems with the SPP is the head unit not the speakers.
I also recently replaced the woofers in the doors because they were blown. The foam surrounds had become separated at the outer edge of the speaker and they were fragile. I live in a hot and humid area so deterioration is expected (even though the car is garage kept and seldom driven). I searched everywhere in the US for after market replacements with rubber or foam surrounds that would drop in the existing housing directly or with modifications but no luck (the speakers have unique dimensions). I ended up purchasing discounted OEM speakers over the internet from a Porsche dealer in Annapolis. You have to purchase the internal plastic grill and the speaker as one unit which adds to the cost. I coated the outer edge of the foam surrounds before installation to increase longevity (
https://www.simplyspeakers.com/speaker-repair-cone-edge-sealer-mi-1291fg.html
). Of course Porsche does not make it easy to replace the speakers. I managed to do the replacement. I did break a couple of the fasteners but was still able to reassemble everything snugly with no vibration noise from the doors. The removal of the door panels is very difficult to do without causing some small scratches in the fragile interior paint. Here is a video I found that assisted me with the removal:
https://www.youtube.com/watch?v=uaabW2CIMl4&feature=youtu.be
Also note this information from Euro Motorspeed:
"Regarding the variations between head units, as it pertains to the harness adapters. Pioneer seem to have done away with a dedicated Power Antenna wire in their newer model head units. Your vehicle however still has a power antenna wire as part of the factory harness, so in order to provide the signal for the power antenna, the "System Remote Turn On" wire which is used to switch the factory amp (or an aftermarket amp) must also be connected to the power antenna. This will allow A.M. reception in most cases unless you live in a very rural area."
