I dunno if your tranny gears are like ours, or which tranny you guys have...but if it is like ours I'll say go 3.90s...I originally had 3.90s in my car and loved them...after blowing 2 rears and putting in a ford 8.8 I didnt have a 3.90 option so I jumped up to 4.11's...I did notice a difference over the 3.90's as it took out some flatspots, but to be honest the gears are too short. I have an A4 and as you know you cant go WOT into 4th gear because of the converter locking up, 3rd gear will wind out to about 202km/h at 6500-6600 rpm which I don't like churning the car to.
Secondly my gas mileage took a BIG hit...I used to get 550-570km to a tank of gas all highway, with the same kinda driving Im struggling to push 500km to the same tank.
I'd love to have my 3.90s back...great performance and easier on the wallet.