Just bought and installed the TST-507 system on our Sonic for our trip out to Colorado.
A test trip showed it would read three tires no problem without the repeater, but to get that right rear passenger side tire, I had to install the repeater. The monitor is rechargeable through USB, small, and bright. Really easy to read. Oh, it's also LOUD! As a test I let about 10 PSI out of a tire and started driving around the parking lot where I was doing brake testing/setup. I turned on the monitor and as soon as it synched up, it started flashing the low tire and beeping loudly. Stopped, aired the tire backup with my Co2 tank, and it read the new pressure and all was fine. This is going to take some of the stress off me while towing these long runs.