rearend gear question

i have a set of frpp 410 gears sitting in my shop. I want to put them in but there is a disagreement between me and the wife about them. of course i want them for off the line power and to help at the strip, what she is concerned with is the fuel mileage i would get after they are installed. now keep in mind i have a 01 gt with a AODE. What would the ball park mileage be with the 410s installed. i get about 18 in city and 22 highway( how i get this i dont know) but we are trying to figure out if we should ditch these sell them (new still in the box) and go with 373s instead. any thoughts

I've got 3.73's on my '02 and I had gotten 26 mpg before on a trip. Usually it gets 24-25 hwy mpg. Looking back, I wish I would have thrown in 4.10's for the "off the line" pull. One of our guys up here had 4.10's and would get around 22 mpg or so. He now runs 4.30's I believe.

I have gotten 24 mpg with 4.30's on the hwy. My in town MPG does suck but don't fear the gear

How much of a pain in the rear is it to install these yourself? Is this a shadetree job or should a qualified tech do it? Thanks.

Qualified tech! The specs that the gears need to be in are so precise that you need special tools to do this.

Will definitely go that route then! Thanks.