I have a Mopar 12 edition of the 300 that came stock with 3.92 gears. What I would like to know is how easy it is to change the ratio to a little less aggressive ratio, maybe like a 3.55 or 3.06. Also, is there any programming that would need to take place after the gears were physically changed? I'm not sure how the car does its reading/calculation for vehicle speed. Any input is greatly appreciated, thanks. The car screams from a stop, but the problem is it also screams at 3000 rpms cruising.