I installed an after market 6 sensor sonar in my SR5 with chrome bumpers. And like most of my other mods, I did a write-up of how I did it.
After Market Parking Sensors (54 pictures) - Toyota Tundra Forum
I went with the silver ones so they aren't easily seen. If you look at the picture in my sig, there is a sonar in the corners of the bumper. I used to use it sometimes when backing up, but since I installed my rear camera, I rarely ever use it anymore. I will use it on rare occasions to be sure I have room in the front right corner. But the rest of the time, I leave the audio off and never open the compartment it is in. I installed the LCD display in the front most sunglasses holder.
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The wires for mine were too short as well, but I just used some coax to extend them.