Hi Scott,
If the car is overheating with a functioning stock t-stat, a lower temp t-stat will not help that problem at all.
If the car is going to run at 220 degrees normal operating temperature with the stock t-stat wide open, it will run 220 degrees with a 180, 160, 140, or lower t-stat because they will all be wide open letting the water circulate.
What you will notice with putting in a 160 t-stat is a bit longer time to reach normal operating temps and larger temp SWINGS on the gauge.
Highway driving on a cool morning will have the temp needle left of center but when you hit stop and go traffic it will get just as hot as when you had the stock t-stat in. Highway driving in cold weather may yield a colder running car than it was designed for. Remember, this device regulates how cold the engine will run, it does not regulate how hot it runs. That is done by fans and heat exchanger (radiator).
Also, with the exception of the Mopar Performance Parts 180 t-stat Photo, the aftermarket t-stats I have seen from Stanton and Cat. do not look nearly as well made as the oem unit and some have had a sticking closed problem.