I installed the 3.54 differential purchased from the Zip group purchase.
I made the break in suggested (Three trip of about 30 miles letting cooling completely the differential between the runs...) then I made 2 80 miles trip always letting cooling it completely. Then made some short trips applying more and more gas pedal....
In the first 30 miles trip i noticed a Whistle...A quite definite wistle (very quite whistle...You need to be with your ears very carful to notice it but i was present...)
After these 30 miles trip, no more whine... OK, the unit is not quiet like the old stock unit, I can say that i can hear from the rear a minimal, minimal, minimal noise.
After about 300 miles I pushed hard and i can feel the difference versus the old 2.73 gears...
I really like it even at part throttle where my car was very lazy...
NO more the old sensation of lugging ...
I tried also on the track (not a real dragstrip...a racetrack with the christmas tree and the finish line at 1/8 .)
When i was with the 2.73 and the 2.73 unit I made passes only with G Tech pro and with the calculator of the Datamaster software.
My best on the street was 2.23 on 60 ft and around 9 sec on the 1/8
I made my best pass with a fantatstic 1.836 at 60 ft. , 8.357 ET on 1/8 mile. and the best ET mph of 81 mph. (I need horses...)
Someone know how to translate this 8.357 on 1/8 to 1/4 times??
Thanks
-Beppe-

 

I don't have my timeslips here with me but, I ran a 8.17 and a 8.22 @ ~84 mph, and the 1/4 times were 12.90 and 12.91 respectively. I would have actually gone quicker on the second run but my shifter was in "2" and I didn't notice until it was long after it should have shifted

 

Very What kinda cruising RPM are you turning?

 

Congratulations on the gear change! I believe that the A4 should have come stock with at least a 3.08 and 3.54 should have been the performance option.
Mike

 

All is near stock on my car...except for headers, gears, underdrive crank pulley. Stock cam and heads...
I found a calculator for translate 1/8 to 1/4 ET...
and a 8.357 is near to 13.10 on 1/4 mile...
Is it possible that my lazy car is so fast??
...and I have to say that it's my really first time at the track..
For compareision I burned all the C5 at the track , except for a C5 with some mod that run consatant 8.10 / 8.20 on the 1/8 mile.
Soon my car will be a 383 with heads and cam.
-Beppe-

 

I'm sure the gears helped a lot, but don't rely on your Gtech too much. They are as accurate as someone measuring with a stopwatch. They are only useful for measuring differences between mods really.

You prolly picked up 3 tenths or so with the gears though. To complement them , you should add a higher stall converter and add a neck-snapping 60foot to that..

 

Low thirteens with headers and gears? It could happen.

 

I know how you feel with your new gears. Like having new legs. youll have a good time with that. Get the stall and youll be busting tires loose at a 20mph roll.

 

I have done 13.4 with my L98. It has dual exhaust with borla mufflers. I don't have headers and still have my 2.59's. I would say that it is definately possible.

 

Thats a good running Vette you have, love the color too

 

Beppe u gave me aconfidence as iam going to install in couple of weeks, i bought the same 3.54 gears from Zip as our GP,
right now my car is in breakin procedure as i did insatalled cam,
heads and rebuilt bottom end.

sami.