Probably the most frequently asked question on every mustang message board, gears are not debatable. 4.10s minimum on a daily driven 4.6L N/A mustang. I’ll get to why in a minute but to realize why there is no debate, we must first look at what gears do. Gears live in the rearend, bolted to the pumpkin and driven by the driveshaft. The job of gears is to multiply the engine’s torque. So with a 250 TQ engine with 4.10 gears, your multiplied torque will be 1025. You might be thinking, “Why the hell do we need that much torque?” Well, the truth is, without a multiplication of torque, our cars will not move. For some visual information about gears and differentials, go here. Most stock mustangs have 3.27 gears from the factory. I have no idea why Ford put these gears in our cars because they’re awful. Despite what some “experts” might tell you, gears will not decrease your top speed in a mustang; in fact, they’ll probably increase it. If you were to top out your car with 3.27 gears, you’ll notice that the power just stops when you shift to 5th gear. This is because you are not in the car’s powerband to pull the car up to higher speeds. Not only will steeper gears allow you to pull quicker but also they’ll keep you in your powerband which will, in turn, enable you to pull in 5th gear; something you could NOT do before. Other experts claim that you will lose gas mileage due to the higher RPMs that your car will now be traveling at on the highway. In reality, you’ll lose maybe 1 MPG at best. By far, the biggest misconception out there is that 4.10s are “too much gear” for a car. These people that tell you this are morons. Those people are stuck in the pushrod days where the cars can’t rev past 5500 RPMs. Our cars rev to 6000 RPMs for a SOHC and 7000 RPMs for a DOHC. Our torque comes on later than the pushrods, hence the need for the steeper gears. Sure, there are instances where you might want to get a different gear ratio if you have a poweradder or are a drag only car, but be it Auto-Xer, Open Tracker or Drag Racer, do NOT get less than 4.10 gears for a daily driven N/A mustang. For those who want to play around with gear ratios, go here. The recommended brands for gears are FMS, FRPP and Motive. FMS and FRPP are the same gears however. Ford has two markets for the same rearend; one is the SUV market and one is the Mustang market. The SUV market isn’t as high performance and not as willing to spend the big bucks for items like the Mustang market is, so they take the gears they make and label one FMS and one FRPP even though they’re the exact same thing. In the end, just get whatever is the cheapest. I recommend getting a shop to do the install as this is a pretty complex thing to do. The install kit depends on how many miles you have on your car. If you have more than 35k miles, I recommend stage 2. If you have more than 75k miles, I recommend stage 3.