Just got my custom tune from Lew installed and it's like driving a completely different truck! Still need to do a WOT log for him. Plan on getting some long tube headers in the future which requires another tune i believe.
I used a superchip programmer on my 07 avalanche with cai/cat back and I wasn't impressed at all. I had some pre-ignition and the engineering guys could never fix it. Plus they didn't allow tq management changes.