Well, I took mine out for the first time and had a best of 15. 8 @ 91. 2. My 2500 4x4 weighs 7320 lbs, and it's a 6spd using 2nd gear starts.
Rattle, Since you have 4:10's you outta try 3rd gear starts. Main thing is to ease the power so you don't spin wheels. I tried 3rd gear but I have 3. 54's and it didn't work out to well. The truck rolled off the line fine, but once the boost kicked up the powermax kicked in to hard causing the tires to spin eating up my 60ft time.
I won't do any 4wd launches. I can't afford to be replacing transfer cases.