I'm going to be installing the central 20 3.9FD gears in a few weeks, and i realize they help with 0-60 and 1/4 times, but they also make the car lose some of it's top speed. My ? is, how well do they work on top end acceleration?, lets say i'm cruising at 60mph and I down shift to 4th or 5th and punch it, will they make it accelerate quicker than stock just as it helps out 0-60?

 

Adding the 3.917 final drive boosts your acceleration approximately 10% in each gear from what I hear. The tradeoff is that you go from a max of like 156 mph top speed to like 150mph. It is such a good mod though because it only helps acceleration. It does not make you sacrifice top-end for low-end or vice versa.

If I'm not mistaken though, it also shortens each gear. I think 2nd stock tops out at 62mph but with the FD installed it may stop at like 58mph or something so to get to 60 you need to shift to third.

Anyone correct me if I'm wrong.

 

depends on the year. my 06' tops out at like 65 or 67 in 2nd gear, the new 07's probably hit like 72 if they havent tweaked the gearing. might be true for the 6600 redline cars though.

 

whered you order your 3.917 anyhow?

 

the 3.9 FD lowers the gearing's top speed from 185mph to 165mph. You won't really nottice a difference since the ECU cuts off speed at 160mph anyway

and yes it'll improve accelleration in 4th, 5th, and 6th gear. It's noticable

 

vivid racing

 

dont add this if u go f/i because first gear is completely useless then, also when cruising, wouldnt ur rpms be a bit higher?

 

10% harder pulls in all gears

 

What about the faul consumsions? any big different after the 3.9 installation?

 

I love my gears. I definetly noticed a difference. My MPG dropped from 23 to 21.