Gear ratio - Gas milage VS Performance

I have a Black 07' GT and got stuck with 3:31 gears. I have since installed a CNL racer intake, Steada pullys, Pypes off road H pipes, Flowmaster mufflers, and a SCT II programmer. Now my question. I am now ready to upgrade my gears. I was thinking about 3:73's because I hear 4:10's are not highway friendly. I use my car on a daily basis and know that changing gears will effect my gas milage. So, if anyone who has installed either 3:37's or 4:10's on thier vehicle could tell me the pros of the power and the cons of the gas milage I would greatly appreciate it. Thank you.

Go 4.10s!!!!!!!!!! With mine being the automatic and my mods closely matching yours I get 24 MPG if I keep my speeds to about 5 MPH over the posted limit. I feel mine is still very streetable as it is my DD. At 80 MPH it tachs around 2800 RPM in O/D...in 4th it tachs 4000 RPM at 80 MPH.

How the hell do all you guys get 24+ mpg?? I get tops 23mpg on the highway from Baton Rouge to Houston going 78-80mph

I wouldnt go 4.10s on the street. 3.73s would be much more easier on the wallet. Although... 3.55s wouldnt be bad either. We've had 3.55s in our trucks and like them alot.

Maybe 3.73s with an auto, and 3.55s with a manual.

I dont own a S197.

Why should I go with 3:55 for 5 speed and 3:73 for an auto? Is 3:73 too much for a manual? Also 3:55 dosnt seem to be that big of a jump from 3:31, would I even notice a diffrence in power?

I REALLY enjoy my 4.10's.

Milage runs around 20MPG. (300 miles per week)
23 if I keep my foot out of it, which is hard to do.

I like running around 60MPH and feeling the car accelerate without needing to downshift. The gears keep the car near the power curve.

I will probably go back to 3.55's when I install a new 5.0 3V engine.

Love the 4.10s! 400 mile trip 20.8 mpg @ 100 mph! Set the cruise & go! Now I want 4.56 to play in town.

2005/2006 Mustang GT's come with 3.55's stock. It's not enough.

3.73's or 4.10's depending on how much gas mileage you want really. I'll probably go with 4.10's even with the drop in gas mileage...just get a better tune for gas mileage probably.

Go w/4.10's!! Seriously, at the most you'll lose 1-2 mpg, and that's with the hammer down all day! I get 22-23 on the highway at 70-80, and probably 13-15 in town. But I've got a manual and I get on it every takeoff!!! That's why you bought the Mustang in the first place, lolol. 4.10's make all the difference in the world. Our track here closed down, but from what I understand, it's like a couple tenths difference. But the real test is how the car feels, and buddy let me tell you it makes all the difference in the world.

I test drove a car w/3.55's, and it wasn't nothing compared to those 4.10's! I have a hard time getting traction in 1st, burn the tires through the first second or two in 2nd, and still light 'em up in 3rd!!!

He said he had 3.31's.

Im almost sure that 3.55's are an option.

I just figured if you had a 5 speed that the 3.55's would be great. But by judging by all the other responses, I'm wrong. Its not that I think 3.73s would be too much for a manual, its just that I think automatics are pretty lazy compared to a manual, and I would think that 3.73s in an auto and 3.55's in a manual would give about the same feel, minus shifting. But I dont know for sure.

Going from your 3.31's to 73's will be a noticable difference. I personally have 4.10's and love them.

I can say from experience that the 4.10s definitely help the lazy autos!!!!!!!!!

whats the price difference in the 3.73 and the 4.10... installed... or just the gears..

i know the 4.10s run around 400-500 installed..

thanks
-B.F.D.M.

prices MIGHT be $20 different. the ratio will not determine the labor cost, but it does affect the price of the gears themselves.

i have 3.55 manual w/ 18" rims and its got some nice go, but i'm not a lite-em-up kind of guy. I've been getting around 23 mpg even w/ hard take offs. However i do think if i was going to pay money for a new rear end set i would go 4.10.

Its just that mine came w/ 3.55 and i was happy it did w/ the 18" wheels other wise i think it would be a pooch. 3.55 w/ 17" rims is pretty punchy, beware 4.10 and 17" wheels i think you should also check into stock in a tire company

I'm using 4.10's with my 5sp manual and the mileage sucks on the highway. I'll be converting back to either 3.73 or the stock 3.55's. I also find it's too much gear for the stock Pzero tires.

I know, I was just saying that he would regret getting 3.55's and that they came stock with the 05/06 Mustang's. In 07 they became a $100 dollar option.

3.73's or 4.10's is where it's at. If you are really concerned with gas mileage just get 4.10's and put a 75-100 shot of the giggle gas on it and call it a day

I appreciate all th input. I am going to go with the 4:10's. I guess if I'm going to do it, I better do it right. I would hate to get 3:73's and regreat not knowing what 4:10's had to offer. I'll be sure to let all of you how it works out. Thanks again.