Try different wheels and tires if possible... I had got a new set of tires on a different vehicle (not the S650) and had issues. I had a set of winter tires on another set of wheels that were fine as a baseline. First, one of the new tires had a big bubble on the inside of the belts, tire guy...
Are you putting it on a trickle charger when not driving for a few days? I put mine on one and got an update (10.1.1)... the first one in a long time... maybe coincidence, maybe not?
While any will work, if you want it properly sized for the size of the S650 battery... about 4amp is the proper size to get.
Yes... there is a proper size for best results and long life. As everyone says a small one will work... I used one that was like 1.5 amp for probably 10 years or more...
https://www.mustang7g.com/forums/threads/amber-drl-via-forscan-and-fdrs-yes.168209/
To start... you will need forscan... www.forscan.org and FDRS (Ford programming software). If this stuff is all foreign to you, you may have better luck looking for someone in your area with the required...
If not tracking the car, save your money... flow formed is lighter and stronger than cast wheels... that said, I have been shopping forged wheels the past couple weeks... for choice of finish/color and perhaps running on a track at some point... but the color choices :thumbsup: , but the prices...
As some have said, air flow through the car helps with the buffetting... open the trunk... but it is an issue with most new cars as they are airtight. Old cars were never a problem... not built airtight.
In case you haven't found them yet, there are threads on here for each color... lots of members posting pics of all of the colors. Search for "Official FULL COLOR NAME HERE Mustang S650 Thread"... just put the color you want in the capital letters.