A custom Tune will fix that the lethargic GM, I have an old 2008 gmc sierra rcsb with 4.8 4 speed I swapped 3.42 gears for some 4.11's and have a blackbear custom tune, all I can say is its a lot of fun, rebuilt trans at 365,xxxkm to 4l70E specs it still going with 410,xxx on the clock. my 17...