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      01-08-2013, 10:10 AM   #48
pbonsalb
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Drives: 08 E90 M3, 99 E36 M3 Turbo
Join Date: Feb 2011
Location: Concord, NH

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Quote:
Originally Posted by Team Plutonium View Post
You'll also loose quite a bit of top speed.
Yes, assuming you need to go much faster than 180 mph.

A 6 Speed with stock 0.87 6th gear and stock 3.85 diff and stock 265/40/18 tires goes 193 mph at 8250 rpm. Changing to a 4.10 diff will reduce top speed at 8250 rpm to 181 mph. Even raising the rpm limiter to 8600 would not restore all of the top speed.

I did not do any of the math for a DCT or its differential options. They could be more or less. I know there are two popular alternative diff ratios.