4.09 Gear in 2016 6m

[Shadowdriver]

I am looking at getting 4.09 gears in place of the current 355 . Have a gt350 intake, catback and a dyno tune (8k limit) at this point. Up until recently it was my understanding it was not an issue and a tuner merely “checks the box” and it’s good to go after the install. But I’ve read recently of multiple cars going into limp mode and that the gear can’t be tuned for . Also have read Ford no longer offers the 4.09 gears. Is this a common issue? I’ll need to drive the car a couple days before I can get to the tuner but while he says it’s no big deal he also has not done a car getting a gear swap. Any input is appreciated

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[Blackout S550]

I have 4.56s in mine. I couldnt drive the car with the stock tune and the shifting felt all off because torque management was fighting it something awful. I could make it to about 45 at 1/4 throttle before it just fell on its face.

My tuner was able to make it happen locally. Both lund and palm beach werent confident that they could handle a 4.56 change. I happen to have a bama lifetime tunes package and they handled it first try and had fuel trims within 3% while i still qualified under their modification list.

Small side effect is that traction control doesnt kick in until wheel speed is about 40mph above actual speed but you get that on those big jobs sometimes.

 

[Blackout S550]

Bama did it with the sct device and locally was done with hp tuners so it should be a universal option with whatever "secret recipe" is put in place.

 

[Shadowdriver]

Thanks for the input, apologies for the late reply. Current tune is HP Tuner based.

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