First off, dealers dont like to swap gears, dealer could get fined, secondly, dealer does not have a way to change ECU fr gear change. Procal or any other tuner will work. Procal is warranty, anyother is warranty void. FYI: Don't pay attention to folks staying NA & doing 4.10's in a A6, they're clueless.. 4.10's in the A6 are equal to 4.40's (if they could exist) in a MT82 car. The first gear in the 6R80 is equivelent to a 3.77 axle in the MT82 car. 3.31's in the A6 are about equal to 3.91 in the MT82 and 3.55's in the A6 are equal to 4.10's in a manual. Putting anything past 3.55's in your A6 5.0 will be worthless. You'll be spinning tires all over. Your not winning if your spinning. 3.73's in the A6 is overkill big time unless 50% of your driving is track only. In fact it's this first gear that is why the A6 is equally as fast as the MT82 in the 1/4. Sixth gear is also same as first in the 6R80. Your mpg will go down the tubes with 3.73's in the A6... Going from 3.15's to 3.31's in the A6 is equal to going from the oem 3.31's to 3.73's in a manual. The difference will be BIG. stock converter. 3.31's are the fastest set up for a fast DD street car NA. 3.31's are still good for light boost (4-6psi) or upto a 75hp shot. Also, going above 3.73's you start losing hp above 4500rpm. Here you go: 3.31 gears, driveshaft, UCA/LCA's, converter, and tune with sticky tires and your at near 475-480 crank hp & high 11's at over 116mph in the 1/4...in cool air and low DA of course.
Yea, its an old thread...but someone will read this!
You are EXACTLY right and did your homework on the gear comments. Guys who post about 3.73 and 4.10 being a correct fit for this model year either dont own a 13-14 GT (I have a 13 GT auto)or have no real experience with gear swaps. Just because a number sounds "low" doesnt mean its incorrect!
Heres my former dilemma and why Im sticking with 3.15...
I currently have a Bama hybrid tune which means HUGE low end power. My tires can spin in 1st and chirp in 2nd, 3rd no problems. 0-60 is breathtaking.
I can buy a really deep gear like a 3.55 or 3.73 and get the same tire spin (way too much probably) at the cost of giving up the hybrid tune...would be a tire spinning mess and I'd be forced to permanently use a lesser tune. Gears take away some gas mileage and your car will rev a bit higher at EVERY speed = more engine wear = shorter engine life. You then must run out to buy 20 inch tires and rims just for that gear swap to function. Who does that?
Dont go above a 3.31, get yourself a "torque" tune and dont get caught up in a number. Tell me later how awesome it is...I run 0-60 in under 4 on occasion - with 3.15s!
V6 - 2.73 to 3.73 or even 4.1, make TOTAL sense. Early model GTs or manuals, 3.73 makes sense. 5 previous mustangs and 3 gear swaps for me. Not this time!