Doesn't matter where you live, the ability for the motor to warm up the quickest is always the best way to go. Don't think of it as an emissions-only piece as that defeats the purpose of its correct operation allowing the choke to come off faster, prevent carb icing, and all-around allowing your motor to live longer. Alter what Ma Mopar did on your vehicle at peril. Best to keep stock items stock, BUT working properly.
Mine rattles also. I wrapped a wire around it and the manifold until I find a better solution. Used 14-gauge galvanized. Been fine for two years and 20,000 miles. And I live in hotter-than-hell Texas. That little flapper door is temp-regulated, and usually is only fully open when ambient underhood temps reach 115=degrees; otherwise it vaires frlom fully closed (heatr manifold air only) to partially heated/cooled. This enables some nicely lean carb jetting, and is VERY good for mileage and engine life.
Not saying you can't "improve", but there is no free lunch. Most remove-it-performance-mods result in increased fuel consumption and reduced engine life without altering carb/ignition timing, etc. There is a balance being maintained with tthe way the factory did it, and an Imperial was right from the factory the first time.