accoring to his profile he has a 94' with a 3.5L
Here's the deal with the restrictor:
Chrysler put it there to reduce noise.
Removing it will not have any noticable performance gain, neither horsepower, nor mpg. In fact, i think somewhere along the lines somebody had their car dyno'd and it came back with a slight loss of power without the restricter installed.
Removing it will make you car louder under heavy accelertation.
I had mine removed on my 95' Concorde for about 2 years with no problems whatsoever, eventully i removed the entire intake box and went with the spectre intake, which made it much, much, louder.
So, imo, take it out, the car will sound throatier under heavy accelertation, even though there will be little to no power gain.