The OEM thermostat other than now being 25+ years old also opens up at 94 degrees minimum that is your minimum temperature. Does not give you a lot of head room for a Hot day etc. One of the most common causes for an FD to overheat.
Accompanied with one of our AST Deletes this is one of the best ways to reduce your minimum temperature and give your FD the best chance of running cool. This will allow your car to run up to 15 degrees C cooler.