GT 3.31 Compared to 3.73

MPG:
I think the biggest influence on MPG is driving style. If you're conservative with the 3.31s and do a lot of cruising you'll get the advertised MPG.

If you enjoy more 'spirited driving' in the city, the 3.31's might actually give you worse MPG than the 3.73's. It makes sense that MPG will suffer more at highway speeds with 3.73 vs. 3.31, but I don't really know how much, maybe 1-2 MPG?

0-60:
To me the 3.73 ratio feels stronger at launch than the 3.31. Afterall, it is sold as one of the 'performance' axle ratio options. I own a 3.31 and have driven a 3.73 geared 5.0. The 3.31 is plenty fast and with the stock tires hooks up well on the street for everyday driving, but the 3.73 delivers a more fun pin-you-to-your-seat feel and I'm certain with the right tire/driver skill combo delivers consistently better 0-60 times. How much faster exactly, I don't know?

You'll find endless debate and opinions on the merits of one gear ratio over another. What's best for you depends on what you want to do with the car and how you drive it. For me personally, the 3.31's are a little too tame, and I'm going to try the 3.55 gears. I haven't seen anybody say they wish they didn't have that ratio?

As you can see I have an 05 with similar power numbers to an 11 with the Techco SC. When I first purchased my car, used, it had 4:10s. I drove it from Houston to Pennsylvania like that and it got in the low twentys on the highway. I do open track with my car and have only been to the drag strip once, so I am more interested in top speed then quarter mile ET. I changed the gears to 3:55s and still got in the low twentys on the highway, although my top end increased about 10mph at 6000rpm. Last summer I changed to 3:31s thinking I would get better mileage and more top end speed. The speed is there at 6k, but the mileage has pretty much stayed the same as the other gears. I glance at the computed numbers but always do the math to check it. I am supprised that the mileage has not really changed. I do miss the acceleration in the lower rpm range thought. Once I get around 3500 rpm the accel feels about the same as the 3:55s did. Its almost like a turbo kicking in. I think thats due to the varriable cam timming in the 4.6. Next spring Im going back to the 3:55s. That gear is the perfect compromise for the setup in my car. GA