Yes and no. To install the mod, you have to "jailbreak" Sync 3 which technically does void your warranty, but my understanding is that the void only applies to Sync 3/Infotainment if you end up breaking something.... for example, even if you install the jailbreak and this mod, Ford cannot deny you warranty repair on let's say, the engine, or the doors, unless they can prove your modification of Sync was the cause of those items breaking, which really isn't possible, nor could Sync break those anyway. They can however, deny you warranty repair of Sync if let's say during the jailbreak process, you brick the Sync unit and it needs to be replaced.
In reality, the changes made to Sync by the jailbreak and mod are easily reversible and unlikely to break anything as long as you follow the directions. And worst case, you can revert to stock if you are worried and ever need to have warranty work involving Sync done. The jailbreak and mod do not require modifying physical hardware, it is all in software so Sync 3 can be reformatted back to full stock.