Gene K

A5 has 0.71 OD. The following assumes locked converter and stock 17" tires.
If you run 1/8 mi a lot you may want to set it up to trap in 3rd.
Once again the actual mph at the finish line is approximately 2 mph higher than trap speed.
Im condensing all gears after the first. 1/8 - 1/4 - Cruise. Im assuming a 6800 rpm limit.

3.73 is 6397 rpm at 87 mph in 3rd (1.54) - 5204 rpm at 109 mph in 4th (1.00) - 2542 rpm in at 75 mph in OD (0.71)
3.90 = 6688 (3rd) / 5441 / 2658
4.10 = 4566 (4th) / 5720 / 2795
4.30 =4788 (4th) / 5999 / 2931

You can also play with this by using different size tires. Its likely the route I would go.
4.10 +28.1" Tire= 6781 rpm (3rd) in the 1/8
4.10 + 26.1" Tire = 5939 rpm (4th) in the 1/4

This is like having a 3.90 for the 1/8 Running it like a 3spd Auto and 4.30 for the 1/4 running it as a 4spd Auto.
For a street tire run the Federal 595SS in 255/55R17 or 255/50R18 to keep the revs down if you dont want DR's on the street.

Caution

I'm sure you have -- you just haven't noticed it yet [8D]

Daniel60

what i meant was I haven't lost any performance from either low end or top end. And it accelerates like a rocket.

06Redfire3V

4.10s = 4 tenths
4.30s = about the same (cuz u wont have as much traction) maybe 5 tenths if u have some DR's

CroDalmatinac

Get the 6 speed trans from D&D and go with 4.30 and lower. INSANE acceleration AND no drop in gas mileage.

Caution

Hrmm -- when I had my stock gears I could take 4th roughly to 140 (like 138) -- with the 4.10's I have to shift roughly at 120 (like 118) ... don't get me wrong I'm not complaining cause Caution does move like a rocket with the 4.10's

Thief_of_Hearts

yikes..I will most likely just go with the 4:10s just to play it safe..gonna stay NA til srping of 09 and want the gears for something play with til the big sc mod.from what I have heard I will most likely go back the stock gearing for better traction and top end.

though it would be interesting to see and feel how the 4:30s and 56s perform,the tech talk is informative and all but I want to know how the car will feel like upon acceleration and see if it's something I can live with (especially when winter comes around again lol)

does anyone reccomend any suspension work if someone went with the higher gears to handle them better??

NELS GT

4.10s seem to be the best from what I've heard.

I don't really have a useful reponse to this thread other than that the majority of people are very happy with 4.10s that ive talked too.

Daniel60

No doubt your correct it's just what I have read and my personal gut feeling you are still pushing this car beyond the 140 mph mark.

Menace

Right now I'm redlining through the trap in 3rd @ 107 mph. Stock 3.55 gears. You're saying that with 4.10s I'd be redlining in 4th gear through the trap? That's crazy.