What's your ultimate goal? Sure, in high gear (overdrive) your RPMs looks good, however, RPMs will be way up in the lower ranges (1-2-3). Where is most of your driving going to occur?

 

I just want there to be more power. I feel like the current setup is a huge strain on the engine and tranny. It's a dog on the highway and I'm looking to fix that. Gas mileage doesn't really concern me, I don't drive a whole bunch and don't mind putting gas in. I don't even pay much attention to my mileage right now. All I know is I get about 290-300 miles a tank. Just looking to make my truck more fun to drive!

 

It's all just math. All the calculators work the same way. So, chances are VERY good that's its accurate.

 

For what you described I would recommend 4.56. I have 4.56 with 35s and at highway speeds I'm about 100-200rpm above factory gears (355) and tires at same speed. If you have any questions ask away.

 

I find this site extremely handy when calculating gear ratios.

http://www.powerblocktv.com/resources/

You enter your current ratio, tires and future ratio. You also need to enter your transmission final drive ratio - 0.69:1