Update (12.12.23): I reached out to FelloStar about the HU not being able to see the OBD2 adapter. Their response was to factory reset the head unit, which I did multiple times. Still no joy. In the end I'm returning it. I was really wanting to like this head unit. Maybe I got that one unit that refuses to connect to anything other than a phone.Other than the HU not recognizing the OBD2 adapter and not being able to customize the home screen other than changing the wallpaper, It isn't a bad head unit. It has really good sound, screen is very bright and easy to see in sunlight. Apps load quickly and screen changes are fast. Definitely no lag.Bottom line: If all you need is to connect your phone, listen to music, use a navigator, (etc.), this is an excellent head unit for that. For that I would give it 4 or 5 stars.This is my initial interaction with the Fellostar M6 Pro.After spending most of the day installing this unit, I was a little underwhelmed with it. One of the reasons I bought it was to run Torque Pro to monitor the OBD data of my MX-5 Miata. Another reason was it seemed to have some muscle compared to my 5 year old Atoto A6 Pro. In this review I'll make comparisons to the A6 Pro and installation into the MX-5.First, the mounting screws supplied were the wrong ones. The supplied screws were M5 and should have been M4 x .7. Have fun finding a screw with that type of head on it. After several hours of running around to different stores, I settled on a pan head M4, which I was able to make work. For the install I used my existing Metra Electronics 70-7903 wiring harness and Metra 99-7506 installation kit. It took me another couple hours swapping out the A6's wiring harness with the new HU's harness, removing the old GPS and WiFi antennas and installing the new antennas, and getting the new HU mounted into the installation kit. Being the new HU is thin, there is much more room behind the unit for the many wires.First boot up was fast and dumped you into a screen calibration. I was unable to get any sound until I discovered a setting to turn on my external amp. Be warned, boot up sound level is set to 15, and when I turned on my amp, I just about blew out my hearing! My amp's gain was set high for the Atoto. Lowering the sound level to 1 (which was comparable to the A6's level of about 7) I adjusted the amp gain for the new HU.There is almost no delay in opening apps or screen changes.The screen is bright and is almost too bright at night, even while dimmed, and I'm a little worried about light glare while driving.After making several sound adjustments in the settings menu, I was impressed at how much better the new HU sounded compared to the Atoto. Being the MX-5 is a convertible, the sound stage isn't very good but you can actually get a decent sound, although I wasn't able to test the sound while driving (I'll do that later and update).Now for the let down...Like I said at the beginning, I wanted to run Torque to monitor OBD data, But I wasn't able to get the HU to connect to the OBD reader as it seems there is only one bluetooth available and it's for connecting to the phone. This is a near deal breaker for me.Next let down is the home screen. You have a choice of 4 different screens to choose from in the settings menu. You cannot set up your own home screen, although you can change the wallpaper.On my Atoto, I was able to set one of the steering wheel controls (swc) to dim the HU display. Since I run with my headlights on, I wanted to have control when the display dims. The Atoto allowed automatic by headlights, dimming by time (settable), and manually through the swc. The Fellostar M6 Pro only allows automatic dimming with the headlights or dimming by time (not settable).I'll update this review after I'm able to spend more time with the new HU.