If you're not sure what gear ratio your car has, there are a few ways to find out. One way is to look up the specifications for your vehicle online. Another way is to physically measure the gears themselves.
To measure the gears, you'll need to remove the differential cover and count the number of teeth on each gear. The ring gear will have more teeth than the pinion gear. For example, if the ring gear has 41 teeth and the pinion gear has 10 teeth, then the ratio is 4.1:1 (41 divided by 10).
If you have 3.73 gears, they will be noticeably smaller than other ratios like 4.10 or 4.56. The difference may not be drastic, but it will be noticeable if you compare them side-by-side.