QUOTE(moethepaki @ Jun 6 2008, 02:07 PM)

I'd leave it dead stock. It's the best way to go on any luxury sedan IMO. Enjoy the ride comfort, the premium audio, the cosy leather interior, and just cruise. Don't try to turn it into a sportscar.
The 300M Special was Nurburgring-tuned, ya know...it's a proper sports sedan.
From Edmunds's test of a 2002 300M Special:
QUOTE
We spent a week getting acquainted with the Chrysler 300M Special and came away impressed with the car. Immediately noticeable is the car's harsh ride and the tendency for the giant tires to wander and tramline on grooved pavement. There's also plenty of road rumble evident in the cabin. But the tradeoff in ride comfort and straight-line stability results in dramatic dividends in handling, and the upgraded brakes on this car are fantastic. We managed to stop the Special from 60 mph in just 114 feet. This is almost unheard of for a vehicle of this size. Despite the 300M's girth and 3,650-pound curb weight, this is one genuinely fun sedan to drive on a curvy road. Grip is astonishing, the brakes never fade and are easy to modulate once you acclimate to the sensitive pedal, and the tightened suspension quells body roll nicely. You can pitch this car hard into a turn without fear, and it doesn't push the way most front-drivers do. We wish, however, that the steering wheel offered more feel and less effort to spin.