2001 Cobra 3.73 question
 

Hello, I'm a new Mustange owner, and new to this board.
I purchased a new 2001 Cobra Conv. and I called a recommended shop in Maryland who told me that if I want to change to a 3.73 gear a new chip must also be installed. I was told the chip was nesessary for the speedo change. Has anyone ever heard of this before? Need some help.