If you get any gear higher than 3.55s, most plug in programmers will be able to set your speedometer correctly with the different gears. Im getting 3.73s put in my 03 GT 5spd this week. Im also going to have the ford mechanics look at my tlok because my rear end has always made a grinding noise whenever i turn at a low speed. Anyone else have this problem? It was pretty embarrassing pulling into the all ford car show making a horrible grinding noise whenever i turned.