I put 35's on my f-150 about 2 months ago and want to change gears now. I was looking into getting 4.30 to get my truck a little lower than stock and I was talking to a guy at a party who goes 4X4 ing and he said that I should run 4.56's. He thought I would be content with 4.30's but said I would love 4.56's. I do about 30% of my driving at about 75-80 on the freeway. Would the 4.56 cause me to tach too high. I did a search and found some guys laid down some charts about ratios and it was a little over my head and was wondering what you guys thought. I have a 99 F-150 4.6L, auto(4R70W). Would love any help and thanks.