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Old 09-12-2016, 12:43 PM   #34
JS440
 
Drives: Black 2014 ZL1 m6 coupe
Join Date: Nov 2015
Location: Minnesota
Posts: 10
I read for days in attempt to find someone that had real world experiences in 3.91's in an a6 l99 car.. most recommended against it with no further information to back it up.
I run my car 1/4 mile at street legal open track days.
Bone stock I was averaging 13.8's at 100-101mph with stock 3.27 gears
I decided to install the gm 3.91 kit against everyones advise. most told me it wouldnt hook and would loose top speed in the quarter mile.
After the install. The GM dealer even reprograms your speedo free of charge!
I brought the car to the track with my new 3.91 gear set installed. Everything is was stock
First Pass was a 13.28 @ 105.9 on a 90* humid day.
Car was a half second quicker with an increased trap speed of almost 5mph.
Hands down the best bang for your buck mod.
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