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Has anyone here changed out their rear gears? Mine came with the 3.31 but I'm considering moving to a 3.55 or 3.73. My understanding is that a gear ratio change will throw off the speedometer which would take a tune to correct, but what I'm really curious about is what ratio you went with for those who have upgraded the rear gears.
 

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The only one I know of for sure is @Sarge and he went the other way, swapping the 3.55 for a more highway friendly gear.
 

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Our Australian RHD Ecoboosts come standard with the 3.55, and I must say it does make the acceleration feel snappier.
When I see 1/4 mile and 0 - 60 times posted by owners of stock Ecoboosts, I often wonder what rear gear they are running, and how much of a difference it does make. :)
 

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You local Ford dealership service dept. should be able to reset your speedometer for correcting the new ratio chosen.
 

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The only one I know of for sure is @Sarge and he went the other way, swapping the 3.55 for a more highway friendly gear.
Yes, I went to 3.31 gears to keep RPMs down a little for all my highway cruising. But my best 0-60 time improved by .2 sec cuz I didn't have to shift to 3rd to reach 60.

Cobb AP lets you correct for gear ratios. There's just one place in the files where you change the number. If you're at all comfortable with the software, it's easy.
 

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Went from 3.15 to 3.55. Highly recommend 3.55s and wouldn’t go much above that. 3.73s would probably be too much gear
Hey! I have 2016 Ecoboost Premium Automatic (not the performance package) and I’ve the Ford performance tune + CAI, I’m considering a differential upgrade and going up to 3.55 from 3.15, how do you go about the upgrade? What are the pros and cons? I’m hoping to eventually achieve top end speed increase (currently, it cuts off at 122 mph)
 

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Hey! I have 2016 Ecoboost Premium Automatic (not the performance package) and I’ve the Ford performance tune + CAI, I’m considering a differential upgrade and going up to 3.55 from 3.15, how do you go about the upgrade? What are the pros and cons? I’m hoping to eventually achieve top end speed increase (currently, it cuts off at 122 mph)
I've not done a rear end upgrade, so don't know all the how tos there, but...

Your top speed isn't governed by the rear end gearing at the moment, but by the factory tune. You need to look into one of the aftermarket tunes before that 122mph top speed will get raised. Once you do that, technically speaking teh 3.15 you have now will both get you better gas mileage, quicker to 60mph, and a higher potential top speed. The 3.55 will be quicker off the line, but because you then have to shift into 3rd to hit 60mph it makes you a little slower to 60. Others have tested this extensively.
 

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I've not done a rear end upgrade, so don't know all the how tos there, but...

Your top speed isn't governed by the rear end gearing at the moment, but by the factory tune. You need to look into one of the aftermarket tunes before that 122mph top speed will get raised. Once you do that, technically speaking teh 3.15 you have now will both get you better gas mileage, quicker to 60mph, and a higher potential top speed. The 3.55 will be quicker off the line, but because you then have to shift into 3rd to hit 60mph it makes you a little slower to 60. Others have tested this extensively.
since I’m in college (and the eco is my DD and only car) and on limited budget, I was scared to consider the much lauded “intercooler upgrade” and “aftermarket pro tune”. That’s why I went with the FP tune and CAI.. but I’m very underwhelmed by the 122 mph top speed and the lackluster performance... is there a safer way to go about this? Any brand/tuner/parts that you recommend?

I have steeda shocks, struts, and mounts, and got rid of the pony package rims in favor of the performance pack matte black rims from FP
 

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hm, yeah. I've had good experience with my Cobb accessport and Pro Tune, but others like other stuff, and they all hit the same kinds of goals, more power and elimination of that speed governor.

Even with the FP tune, I would recommend replacing the stock intercooler with something better. Any of the "street" intercoolers can be installed while keeping the active grille shutters in place, so the dealer wouldn't even notice it. Cooler charge air temps give you better performance. I like all of the Steeda stuff, and I know they have a tuner and calibration files also, though I don't have any experience with them.

Ultimately you need to decide what direction you want to go. My eco is also my DD, and I've never been concerned with any of my upgrades, though I will always recommend doing lots of research before dropping that hard earned money on anything. There's nothing so frustrating as paying for the same upgrade twice because you realized it's not what you really want/need. I don't think you can even resell the FP tune like you can with the Cobb and others.

Really I can't offer much advice other than maybe it's time to step back and re-think/re-plan your upgrade path. Asking questions is always good, and there are a ton of threads here with information about how people have gone about the upgrades they've done. It's never a bad thing to hold off on an upgrade until you can afford the right part, or a good sale comes along...
 
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