Lower Degree Thermo Without a Tune??

I'd like to get a lower degree thermo (just 180), run water wetter, and get a Goodyear Gatorback Poly-V Belt (which supposedly helps it run cooler), but I'm told that no one does PCM tuning for the 3.4. So would it run rich if I put one in without a tune, or woould it just not use it's full potential? I don't know why, but somehow reading posts on this board, I got the impression that I shouldn't put a lower degree thermo in without getting it tuned. I certainly don't want to lsoe gas mileage.

I don't think you would have any problem running a 180° thermostat without any other modifications. Obviously, you can monitor the gas mileage to see if it changes. Not sure how the belt will make it run cooler, unless the existing belt is slipping. The Gatorback is a good belt, though.

Thanks Shoebox.