By going down one in front and up three in the rear you will increase you rpm at 75 mph in 6th by about 1,000 rpm. So at 75 mph you should be turning about 7,500 rpm.
Oddly enough, I have a '95 and went from 15/40 to 15/39 and I am still able to get the front end up in 1st and 2nd (some times unintentionally).
Oddly enough, I have a '95 and went from 15/40 to 15/39 and I am still able to get the front end up in 1st and 2nd (some times unintentionally).