180 is fine. I have had an engine builder I trust tell me never run one colder than 180* as it will actually hurt performance (he is a pro that does racing engines, and many many wins) the only reason the 160* stats did anything was they made the computer dump fuel (I love when the guys have a wide band O2 sensor and a 160 stat as the pcm basically ignores the o2 sensors in warm up mode)