It's good if you have lowered your stang. It helps steering..it actually eliminates bump steer....check out the link below.
A lot of mustangs expirience Bumping steering whe n lowered. What happens is when then car is lowered then the geomerty between the a-arms an tierods has change. Bump Steer kits are designed to get the tierods back in to the same plane as the a-arms. Steeda Bumpsteer Kit (94-04 Mustang) 555-8104 - Free Shipping!