RC5522

Hey I found this while out and about on the net.
I take the credability of these guys more than almost anyone.
This is from 5.0 fords Magazine online

Im going to start this out with Gear Ratio Talk from them,,
This should be a good quality answer for people looking into gears... Very useful and a sticky could help answer alot of these topics we see about gears..


OK, what are the near universal recommendations from our tuners? Topping the list was an old favorite, rear axle gears. Always the best bang for the Mustang performance buck, moving to lower ratio gears in the ol' 8.8-inch differential is reasonably affordable and gives an immediate, unmistakable increase in acceleration performance. The devilish detail is which gear to buy. Stock, the New Edge Mustangs, both V-6 and V-8, came with 3.27:1 gears. They really are a good compromise between low-speed acceleration performance and freeway flying. By keeping engine rpm relatively low on the freeway, the 3.27 gears do a major part in promoting fuel economy. Performance ratios available for the 8.8-inch differential are 3.55, 3.73, the newcomer 3.90, and 4.10. Many 5.0 traditionalists will advise you that the 3.55 is the best all-around gear, but that is with 5.0s. The less torquey, smaller displacement 4.6 engines need more help, and so the 3.55 is the Two-Valve's best economy/slight performance ratio gearset. In the wide-open West, where 50-mile commutes are not uncommon, drivers would be happy with 3.55s simply because they're spending so much time highway cruising and $3.00 for a gallon of gasoline is a real threat, but there's more performance to be had. If high-speed freeway driving is not a major consideration, which is typical in the East and Midwest, then 3.73 gears are the default ratio. These will definitely give a noticeable boost in acceleration more than the 3.27 cogs while still not driving you batty on the highway. In fact, if in-town running around is really all you do, the 3.73s may actually improve your mileage--assuming you don't pull a John Force launch from every light--because the engine doesn't have to work so hard to get the car moving. Finally, there are 4.10s. Knuckle dragging gears for sure--don't go here if endless hours of freeway driving figure in your plans. On the other hand, if brutal three-gear blasts are what you're into, or if you run a 28-inch tall slick at the drags, then 4.10s will cure what ails you. Typically, automatic transmission cars want one more step in gear than manuals, and this is where the 3.90 gear ratio comes in. Offered by Pro 5.0 (yep, same folks famous for shifters), the 3.90 cog is relatively new to the Mustang scene, and is proving an excellent gear for automatic New Edge cars. It's also a good option for manual-transmission owners wanting everything the 3.73s can offer, and who might really want the 4.10s, but are afraid of the high highway rpm and resulting fuel burn. In that case, the 3.90 is just that "little bit more" without having to go all the way. And if you are from the old 5.0 school, don't sweat the lower 4.6 ratio recommendations. The 4.6 engine is happier turning higher rpm than the 5.0, so more gearing is welcomed. With the rear gear change comes a need to recalibrate the electronic speedometer. This is where some sort of electronic tuner comes into play, the Diablo-Sport Predator was one we heard plenty about, but the SCT Xcalibrator is popular as well. Not only does the flash-tuner fix the speedometer, it also cures the check engine light issue brought on by off-road[/align]

beastzilla02

i want to get 4.10's but after reading that i think ima go with 3.90's. cuz i drive on the freeway 5 days a week for a total of 20 miles a day.