If you want a nicer looking, cushier headrest on you 3IS you can simply swap them out for RC350 headrests. They fit perfectly and have the same 3 setting adjustment built into the headrest. The leather match (color and grain) is perfect along with the white stitching. What bothered me a bit about the 3IS was the hard headrests, theres very little cushion. The RC350 headrests solves that, it feels so much better and the as an added bonus it's a bit fancier looking.

ALL RC350 headrests are the same, doesn't matter the year. They will will fit ALL 3IS models. These can be had for about $120-200 for the pair on Ebay.

Here's what they look like in my 2021 IS350.

 

I have this set of RC350 headrests for sale if anyone is interested. It's in the marketplace.

 

why? did you put the original headrests back in the car?

 

Decided to sell my car so getting rid of the small upgrades I've done to it.

 

Something to consider is the headrests are engineered as part of a package along with the rest of the seat so any change in geometry or "softness" could impact intended kinematics during a whiplash event so could have unintended negative impact. Seat backrest and seat bottom geometry and stiffness is also very carefully tested as to prevent certain scenarios as slide out for example. And any change in the overall system may have an impact. Not saying that would be the case here but it is something to consider. Without having access to the manufacturer's/suppliers secret and proprietary test data and information, we won't know for sure what impact such a modification would cause, so to speak.