[4rd SVT]

For me, I noticed anything beyond 64GB does not work on my sync.

Wow, I'm using a Samsung 256gb flash drive with about 200gb of mp3 tunes loaded on it and don't seem to have any issues at all.
But I'm using the front lower "solo" USB port by the puka though. Plus mine is the NonNav/Sony version & won't update to the latest and greatest either... I guess that's a plus for me.

Samsung 256gb Grey Flash Drive

I only have a slight issue if it's [Samsung flash drive] not been plugged in the same USB for some time... takes a minute to recognize before the last tune I played comes back on.

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I only use the armrest/center-console USBs for charging only... although my display wants me to connect to which ever iPhone is plugged in there.... I have to scroll back to my flash-drive option every time.

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The OE double USB assembly is held in with a clip... get yourself a tiny or jeweler-size [short] flat-tip screw driver... gently poke & pry... it comes up when you press the clip in....

I orginally pryed mine out 'cause I wanted to see if I could convert it from "two" to "four" ports...wanted to see what Ford used & IF I could come up with an assembly so everyone could charge their stuff.

 

[Atomicinternet]

I can play MP3s off just about any size USB, but I can't install Sync updates from anything over 64GB. I'm guessing the update mode of our APIM doesn't play well with large size thumb drives. I have been able to update successfully with FAT32 and NTFS file systems though, so the exFAT isn't really a requirement for me (although the Cyan Labs tool always formats to exFAT)

 

[nicklulu]

I use the SanDisk Utra Fit USB:

So it does not stick out as much: