Rear end noise

rear is a 7.25". I just swapped my 2.76 gears for a set of 3.90s from Motive Gear. They were buzzing or growling or whatever you wanna call it pretty good and when i got under 10 mph i could actually feel the vibration. I pulled the cover off and the axles out and reset my backlash by putting white grease in the ring gear and turning it around. The pinion teeth seemed to be making contact right in the middle of the ring gear teeth, like the picture shows. I am still getting the noise, but i can't feel any vibration at any speed anymore. The noise occurs the loudest during decel but also during accel. I'm using 80W-90 oil. The contact pattern looked right so do these gears just need to break in maybe? Should i switch to 80W-140? Btw, the car hauls *** with the new gears lol. Keeps the tires loose all the way through first but lets 'em catch just in time for the 2nd gear squawk.