Howdy. I have 2012 Silverado ccsb 2wd. This originally was a 5.3 truck and it is also a wheelchair conversion, so is very heavy. I purchased a duplicate of the set up that Mike from New Era Performance installed on his 2012 Sierra. This is Whipple currently pulleyed at 10psi, LS7 head gaskets, lifters, IDE 725 injectors,ARP head bolts, complete DOD delete along with NEP custom blower cam, Nick Williams 102mm tb, NEP nnbs truck intake,ARE 1 7/8 long tube stainless headers and catless y pipe, Alky dual nozzle meth kit and 2 gallon tank. All of this is installed on a Gen 4 4.8 currently running through the stock exhaust sans cats. Due to the lowered floor for the wheelchair conversion the truck has a 3 inch body lift, this forces you to embrace the 4x4 style. Currently it has an additional 3 inches of lift with Bilstein shocks and Hellwig rear sway bar. I have 20inch wheels with Toyo 12.5x35-20 Open country tires. Currently with ongoing tuning from NEP it hits 0-60 in 5.1 sec and 100 mph in 13 flat. Not too bad for flat footing a nearly 7000 lb truck. In the next couple of weeks I will be adding a DSS drive shaft, driveshaft hoop, 3.5" Duramax exhaust with Magnaflow muffler and swapping to my 14psi pulley. Finally here is my question. Currently it has a G80 and 3.42 gears mated to the 6l80e. I am considering swapping in a Trutrac and lower gears. My research suggests 4.11 up to 4.56 gears with this size tire. Due to the amount of power I am putting down, what should I go with? Thanks for bearing with me.

 

now with 6l80e first gear ratio of 4.02. drive ratio now in first is 13.74 with 3.42 with 4.11 will be 16.52 and 4.56 would be 18.33 .lot of gear for blower .i wouldnt change

 

Go to tirerack.com to get the true diameter of your tires and then go to wallaceracing.com automotive calculators, gear, mph, rpm, tire diameter calculator to compare.