Gear Ratios

Well my el-cheapo $100 3rd member with a set of 3.91's isn't panning out. After a little use and driveign for a half hour its starting to howl nicely. I was hopeing I could pull off highway driveing but the revs are far too high. So I'm thinking of a set of 3.55's and leanign towards an already doen 3rd member. Anyone have any advice?