Is there an advantage to changing the stock thermostat to a lower one like 160 or 180?

Answer 1

The manufacturers know what the operating temperatures their engines should be. In theory, a lower degree thermo. will reduce the temp. of the fuel-air mixture resulting in more horsepower. In reality, reducing eng. temp. below specs. won't allow internal parts to properly expand. That means sloppy bearing clearances and improper piston ring seal. On a fuel injected car, the ECM would be fooled into thinking the engine never fully warmed up(it won't), keeping the f\a mix too rich, that hurts horsepower.