I know this question has probably been asked hundreds of times on here, but I need a solid answer so I had to ask again. I really want to swap out my factory gears in my 03 mach 1 to 4.10's. The probem is I like to cruise at 75-80 mph on the highway. Basically my question is where exactly will my rpm's be cruising at 75 mph. I have been getting mixed answers ranging from 2500-3500. If its 2500-2800 I think I could take that, but 3500 is a bit high to me. My rear tires are 295/35/18. Plus I plan on doing a procharger in the next year or so. Am I better off going with 3.73's, or is that just a waste of money going from 3.55 to 3.73's? I wish i could ride in someones car that has 4.10's, then I would know exactly how its gonna be. Unfortunately none of my freinds own stangs. I know this sounds like a newbie question, but Im not a newbie. I just have never done gears in any of my stangs yet... Thanx