DDH is right on the money.

If the member doesn't own a 603, ignore the advice.

Mine basically does the same thing as yours. On a warm day, it will climb right up close to 100°C. when doing 0-50 runs off succeeding stop lights, with normal acceleration.

However, it won't go above 100°C unless you are on a very long upgrade using very close to maximum continuous power. In such conditions, at 80°F. ambient, I have observed a maximum of 105°C. after five minutes of this uphill abuse at 70 mph.

Your thermostat is fine. If the temperature stays at 105°C. or less, the fan clutch is probably fine as well.

The only thing you can do, if you are very ambitious, is to pull the radiator and thoroughly clean all the fins. This is not an easy task and requires compressed air and/or a light duty pressure washer. It takes a couple of hours to do it right.

What ever you do, don't start spending a bunch of money to fix things that are not broke (now where did I hear that before?? ).