on most of the 04's you only change the stat not the housing. unless you get a mut that has a little of both 03 and 04. i had a 160 stat in my silverado and got 20 mpg on the highway with the cammed ls1. and on the dyno 1 degree of timming set me back almost 20hp. then took that 1* back out and gain the power back. i thought that was crazy.

 

I am putting my 180 thermo in today, and i am gonna retune my fans, what temps should i have them kick on and off? What are some of your guys' settings?

 

i would take the stock settings and subtract the stock thermostat temp then add that amount to your new stat and punch in those numbers. if you don't have the stock tune number try the hpt repository(spelling).