I tend to lean more in your camp on this personally. However, if the OEM navigation is a priority or preferance we do buy back the old APIM through our trade-in site
https://trade-in.infotainment.com/products/ford/
and it typically has good value on the resellers market as well (Ebay, Amazon...
Both these links are great resources but he has Sync 3 already so the conversion to gain Nav is actually quite a bit easier. It just requires an APIM swap and the APIM to be programmed to the new vehicle. (Maybe a map update)
Infotainment here,
We are glad to hear you are considering this kit, this is one of our top sellers.
https://infotainment.com/shop/interior-accessories/infotainment-radio-upgrades/2016-2023-ford-mustang-sync-3-gps-navigation-upgrade/
Many people have transitioned to the Google Maps, Waze...
I know I am a bit late here but if you are still deciding, we offer an OEM option.
This is the link for 15-18. What year is your Mustang? If you are interested you can use the code exclusive for forum members mustang6g10 for 10% off...