The TH350 and TH400 have 2.52 and 2.48 first gears respectively, closer to what the M6 has. The 4L60E has 3.06, big difference.

 

i say go for it i love the 4:10's i had them for about 1 1/2 to 2 yrs then the tranny took a crap. so now i'm going TH350 it should be interesting going down the road with this tranny and gear setup. lol oh well the gas stations will get to know me very well.

 

i'm getting 3:73 gears with a new rear end cover of course and a 2600 stall.

 

my impala has 4.10s with a Vigilante 3200+ stall converter in the 4L60E. I'd say that it hooks pretty good considering the low power and high weight. I got a 1.699 sixty foot the last time I was at the track I was on 28" street tires even.

The best that I was able to do with 3.73s was a 1.82 sixty foot with 26" ET Streets.

 

will i get about a 10 HP increase with cutouts on a random tech cat back system and stock y pipe and headers?

 

i am also running 4:11s 2800 vig stall in my auto .it isnt that bad the only problem i have is the trans go shift kit set to race it spins the tires all to hell from 1st to 2nd then rattles your teeth from 2nd to 3rd.but if i launch in 2nd it hooks real well and then barks in 3rd

 

How can you launch in 2nd with an A4, manual shift valve body?

 

I run a 3200 on 3.23s, I cant hook street tires at all, any try at flashing the converter on street tires from a dig will get the car kinda sideways prety good. I cant imagine throwing in gears to the mix and hoping it would hook any better. From what I have seen 3.73s work great in these cars with the auto.

 

yes sir i have a manual shift valve body works great

 

I've got 4.10's with the A4 in my car.

Believe it or not, I got my BEST 60' time EVER with street tires!!!! With my BFG DR's, I only cut a 1.94 I think, vs. the 1.92 I got with my Hankook streets!!

Honestly, I haven't lost that much traction. You see, if/when you break the tires loose with high gears (3.23's or 2.73's) then they are spinning faster in 1st gear per given RPM. SO, even though they may break loose with 4.10's, they technically aren't spinning as fast, and I've found they'll hook back up quicker and easier!

Also, surprising as it may seem, I really need a stall. The reason for only cutting ~1.9x 60' times is that my car hooks too hard off the line, and bogs down the engine for the first couple seconds. A stall will fix that for sure. Also, I still ran ~13.5 - 13.7 on a couple Friday nights at the track when the conditions weren't so good, but as you can see in my sig, I cut .4 seconds off my best stock times in good conditions.