That is my next mod.....4.56 gears!
How dose the 6.1 cam run in your 03? do you like it?
It runs real good on the SC so far. Before my Gears I ram a 6.58 0-60 with 3.55's on the 6.1 Cam, then with Gears and switch to Crazy Spartan I managed a 6.08 at a high level of elevation too!.
Haven't done a run yet with the 6.1 back in her but have a feeling it would fair just as well. I'm not knocking the Crazy Spartan but it gave me some grief with the supporting mods I selected.....anyway I am pleased...yes and my Truck doesn't throw codes, idles great, pulls hard up to 6400 and has lots of Heat, for the coming winter.
I still get the occassional Limpe-Mode Gremlin even with the 6.1 and am sure it is related to the Ported TB.
Your Gonna want some real sticky Tires for those 4.56's/4.88's or you'll be smoking the tires alot as a Mr. 2wd.