I notice a difference in the heater temp between a 195 and a 180, but it wasn't enough to make me want to go through the trouble of installing a new tstat seasonally. 180 is still plenty warm in my opinion. Others might prefer it to be hotter though I guess.

 

i found that the best for my truck was the 93 octane tune and 89 octane gas.

 

I'm curious about the tstat as well. I'm fixing to buy a sct but my heat doesn't get real hot anyway so I can't afford to lose any lol.

 

As near as i can figure,the 180 thermostat would just help with spark knock,keeping the engine a little cooler?? I am gonna keep 195 as just test the water on this.

 

Don't hold me to it but I heard that the 180 somehow makes the computer run a little richer.

 

like you guys, I may be wrong too, but I'm thinking the 180 is there to reduce the chance of knock- The SCT advances the timing with it's performance tunes, and every thing that can be done to keep it from pre-ignition is a precaution.. the more advanced, the higher octane needed..

 

For 5.2 and 5.9 engines, you'll want to have a 180 tstat and ensure your plenum gasket has been fixed or isn't leaking. This will help reduce the chance of spark knock with the premium fuel tunes. It may not help mpg so to speak, but will aid in performance.
That's part of a email I got from Sean.