Supercharged L31 5.7

Hello.

New to HP tuners.
I have a 2000 Chevy K2500 that I just installed a vortech supercharger on.
I installed the inline fuel pump and the pressure regulator downstream of the injector.
I seem to hold good fuel pressure at WOT 50-55psi but my wideband shows 15.0 at WOT and pretty much hangs around 16.0-16.5 during normal driving.

Truck runs and drives fine but I'm concerned with it running lean.
The kit came with this little black box that pigtails into the MAF but it doesn't seem to make a difference weather it's plugged in or not.

Has anyone ever worked with tuning something like this?
Any help would be great. I'm new to tuning and I'm going to start running a data log this week.
Thank You