Without the fan mod, your temperatures will rise to stock temperatures in slow traffic or stop and go but if you are moving fast enough for good air flow through the rad (speed depending on the air temperature), you will run at the thermostat temperature and get the performance boost. I had my 176 degree thermostat in for a year without the fan mod and with the type of driving that I do, I almost always ran at the thermostat temperature. I mainly wanted it for passing power on the highway, not stoplight to stoplight drag racing. Now that I have the Predator, it was simple to change the fan settings so now i have it all. Bottom line, the thermostat mod is cheap and easy and well worth doing even if you don't do the fan mod.
There are many threads on these thermostats. Look for the original thread by Meister, the acknowledged expert on the thermostat situation. I also recall there being a thread with pictures showing the swap. The best piece of advice is catching the spilled coolant in a plastic bag when you install it. Then you can return it to the reservoir with almost no loss or mess. Also remember to put the thermostat in with the bleeder hole up.
