Lots of good tuners on here in the vendor section, I prefer the smaller companies like Moonshine, no charge for upgrades like the larger companies.
If you have the patience wait till a used V2 comes up for sale, this way you're not obligated to one tuner. I waited for a used V2 and had a member on here calibrate my stock just a little with a DSP5 tune. Cost wise for me around $750.00 (V2 and the tune) and I can tweak as necessary. I'm using an old laptop with Win7 used for EFI and the truck only....
JoshH Top Notch Garage in Van Texas also a member here