im in the same boat, but even worse im stuck with the 3:55s

whats gas mileage like with those 4:56's?

You have the 3.55's nim?

This one is talked about A LOT and a search would probably show that this question is probably in the top 5 as far as how often it's asked.

The general consensus is that you can expect to gain a mpg or two in town/city driving, remain about the same in combination and light highway, and maybe lose a mpg or two on heavy highway driving (70 mph+), which is about what my experience is. Although some report no loss of mpgs no matter how fast they travel the interstates.

A LOT of people do not do this mod in the belief you lose mpgs, but with the 545RFE essentially having two overdrives, this is simply not the case...