are 3.90 gears good??

[40thannstang]

im thinking about getting sum 3.90 gears for my 04 mustang gt with bolt ons.... are they good??? do yal recommend them ? also would the hypertech programmer fix my speedometer for the 3.90 gears? i know it does for 3.73 and 4.10's???


any help???

 

[svtbronco2]

i like those gears. if you have stock wheels and tires, u'll feel them and it won't kill your gas miliage too bad. if you got fatter tires on the back or slicks, i would go with the 4.10's