Quote Originally Posted by SgtMarshal View Post
the stock thermostat runs at 195 degrees, the 160 is too cold, and the 180 doesn't drop the temperature that much. if your coolant system is running properly, then 15 degrees colder isn't going to make a lot of difference. plus, you have to tune for it so you don't get a check engine light.
I've never had to tune for a 180 other than the fan settings. 160 will give a too cold code but not the 180.

I doubt you'll be able to pass emission either with the cat that comes with your headers in Cali, cali doesn't count when companies say "50 state legal" but you could have one welded in that is California legal.