I installed the full Boom Mat headliner maybe 5 years ago and I will say it definitely is cooler on warm days and warmer on cold ones. When I put the sunrider top on the noise is very noticeable. Wife thinks a window is down.
I went with Bacon for 2 reasons. One: it's breakfast time and I am hungry. Two: I came from a soft top convertible to a hard top Jeep. The Jeep is quite in comparison and I don't see a need for a headliner.
It's not massively quieter with a Hotheads Headliner in my rig with a SOT. I still need to get some "after" measurements at 85 MPH when it's not extremely windy out though.
I’ve been curious about the Coverking Topliner. But the amount of dust that gets in the Jeep even with the windows up on our local trails makes me think I would regret it.
I installed the Hothead Headliners with their Assassin strips and and the rear side window panels. It made a noticeable improvement with noise and it helped to regulate temperatures inside better. I then installed a Bestop Sunrider and the road noise went up again. Hothead Headliners just released a removeable quick install headliner for the Bestop Sunrider and it cut the road noise back down again and made it cozier. The Hothead Headliners products are top notch.
Bought my Wranglers used with Mopar headliners already in it. Helps a little with heat. Would not pay the $ Mopar wants for them. I put sound deadening/insulating material under them directly on the hard top and freedom panels and that made a difference. Bit more heat resistance and the cabin feels more solid. Stereo even sounds better. Basically I created my own assassin strips from less expensive materials used by car stero enthusiasts for decades.
As an experiment, I cut up and duct taped in a section of moving blanket over the roll bar. It doesn’t contact the hard top. Then drove from Colorado to Montana against a strong headwind most of the way. The soft material did help break up the sound reflecting off the hard inner surface, (There is probably some wind noise coming through the top as well) but it was offset by wind noise coming from the doors.
Next experiment will be installing some weatherstripping around the doors, driving around, removing the moving blanket, and taking another drive.
Depending on results, I might consider drilling holes in the top and spraying foam insulation inside to increase density.
I had the shields installed when I ordered. Had them in the last three Jeeps. Reason being my dog. I belong to a SAR team and my dog is a SAR dog, she will spend hours in the Jeep sometimes. Our First hard top wrangler had a black top and no heat shields. It was terrible in the SW sun. First thing I did was have the top painted white to match the Jeep, then installed heat shields. There was a noticeable difference in heat. On really warm days I also use a portable AC cooler. I’m outside sweating and the dog is happy and cool
I put the Bed Rug headliner in the Pumpkin about two years back; my wife immediately noticed how much quieter it was. We just picked up a ’23 Sport S and installed the Boom Mat which also works very well.. it also improves the sound quality of your entertainment system. Are they necessary? No, yet they do make the Jeep a lot more comfortable.