I purchased the Leather Magic Deluxe Repair Kit and reconditioned the seats in my 2003 Box.
https://leathermagic.com/leather-repair-kits/#!/Deluxe-Leather-Repair-Kit/p/49974297/category=13262202
I have no affiliation with them whatsoever, but am satisfied with the results. Basically you clean the leather, prep the leather, clean again, sand, fill, sand, fill again, sand and clean a final time. Dry with a blow dryer after each cleaning. Then you apply the coloring agent (the Deluxe kit has the pre-mixed Porsche factory colors - Savanna Beige for me) with a foam brush into the nooks and crannies. Dry with a hair dryer. Then apply VERY light coats with the aerosol sprayer. This was a little tricky. I found short, quick bursts worked better then a continual side to side method. You should practice a little before this step. Light spray, blow dry, repeat. I did "re-perforate" with a small nail some of the perforated holes that were covered where I sprayed a little too heavily - fixed 'em nicely.
Here is the passenger side before (note the nasty spot which was caused by yours truly when I over-rubbed some cleaner trying to get a small spot removed):
Here is the passenger side after:
Drivers side before (note this was after the "leather prep" stage - it wasn't quite this bad to start, but the prep stage does remove some original color and makes one think "there is no turning back now"):
Drivers side after:
I am going to let them cure for 48 hours (as recommended) and then apply the conditioner to soften them up a bit.
Not perfect, but I think they came out great and I can live with this - provided they hold up. Only time will tell!