Living with 3.91's

You guys are scaring me, i want 3.91's bad, but i wanna be able to drive on the freeway.
3:91's and Nitto P275 60R15's (27.9") for reference:
50mph @ 2600 rpms
55mph @ 2900 rpms
60mph @ 3100 rpms
65mph @ 3300 rpms
70mph @ 3400 rpms