I don't know the weights of the two, but with only 1" difference in diameter, i'd bet my week's earnings (i have no job now
) that the 17" are quite a bit better. What year stang, the 16's are aluminum and not steel, right? I'm pretty sure Ford only made steel 15" wheels from 94 to about 96 and not 16". if aluminum, you're good to go i'd say.