I am FAR from being an expert! But if you understand how things actually work, and WHY, then you can understand how to logically make them better. Designs are always based on compromises. Some of those compromises may not be based on what YOU want, so perhaps you can change the design to be more in line with what YOU desire.
The difference between a 160 degree and 170 degree thermostat will be negligible since this really only affects the temp that the thermostat opens fully, but still, ten degrees is ten degrees. Why are you doing this in the first place? Personally I would rather my cooling system open up at the coolest reasonable temperature possible. Heat just is not good for most things concerning wear and longevity. So the 160 seems the logical choice to me. In my opinion, the lower the temp whereby coolant flows through the engine, the better.
Now I'm sure the thought pops into some people's mind to just forego a thermostat completely. Sure it's nice when you live up in Montana and want your car to heat up as quickly as it can so you don't freeze your buns off when you drive into work. But here in Florida, well, it's probably rare that you even use your heater. So why not just remove the thermostat completely? Well, even a fully opened thermostat, no matter what the opening temperature, does act as a sort of restrictor plate for the cooling system fluid. Without it, there is evidence that the coolant doesn't stay within the radiator long enough for the radiator to do it's job of cooling down the fluid. Remember that not only is the coolant fluid making contact with the inner surfaces of the radiator trying to shed the heat, but it is also in contact with the HOT surfaces around the cylinders that are generating a LOT of heat from each controlled explosion within them. The radiator HAS to shed more heat than the coolant is picking up from the engine, because otherwise, the coolant will try to reach the same temperature as the flames within the cylinders. You REALLY don't want that to happen. So paradoxically, removing the thermostat completely can sometimes make your engine coolant run hotter than with it in place because the radiator doesn't hold the coolant long enough to do it's job. I suspect this is most likely the case with a puny stock radiator, but remember this is a SYSTEM, where all parts have some effect on the outcome. There are actually a lot of variables at work if you think it all through.
If you do a lot of city driving, changing the set points for the coolant fans by reprogramming would be beneficial. But generally speaking with a stock system, if your fans are running while you are driving down the freeway, something is wrong with your coolant system. Or if they have been aftermarket reprogrammed, they were not programmed correctly for realistic temperatures. The fans are there to take the place of naturally flowing air through the radiator when you are not driving at speed. Sitting in traffic there is very little air flowing through the radiator, so the fans are designed to emulate this airflow by forcibly PULLING air through it. So if your goal is to reduce your coolant temperatures, no matter where or how you are driving, then the fans do need to be addressed for those times you are not driving at speed for the airflow to allow the radiator to shed the heat from the coolant into that flowing air stream through it. The new set points for the fans will have to be determined by the new operating temperature of your coolant system. Just make sure the settings are realistic and you don't wind up burning out your fan motors because they have been set TOO low and run nearly constantly because the coolant system just can't meet the unrealistic goal you have set for it.
