Grease the freehub body. Google it. Many ppl have gotten their wheels a lot quieter when coasting. Removing the freehub body is a piece of cake too. Not tools needed (expect the one to get the cassette out)
sure it’s greased. But sometimes ppl add more oil or grease (i’ve heard both) to make it a lot more silent. Google “Quiet freehub body grease” and you should see a bunch of threads and recommendations on which grease/lube to use. Don’t use your chain lube!
People now alot more than me but when we had this issue we called Zipp. It was a “bearing load” issue. Within the hubs, the bearings have a load that can be set. I was told to see if the wheel, when tightened down all the way, has the slightest bit of noticeable side-to-side wiggle. If not, the bearing load is too high and needs to be adjusted (less of a load), usually professionally. Do not confuse this with “I tightened up the wheel too much.” It should have this very slight noticeable side to side wiggle even when tightened all the way. You can also look this up on Zipp’s website. It basically means you bearings are set to tight within the hub itself, hence self created pressure/resistance on the bearings 24/7 and not matter if the skewer is tight or not.