I am currently running a SCT xcal II with custom tunes from Matt Geouge at Spartan Diesel Technologies. I love its speed and ease of upload/download and general layout of the tuner.

I have also run the Superchips SCMT 1704 and loved it for a stock application. (no mods what so ever) When Jim Ferrrao was in charge of the product, he would customize a few specific parameters free of charge, but you had to send the tuner back. It seems that once he left to start his own business, Superchips customer service went from above and beyond, to good.

Mine started at ~2500 miles with an Edge Juice Platinum w/Attitude and Hot code. At ~3200 miles I added NOS with it. At ~5200 miles, the tranny was shifting funnyand felt like it was slipping. I purchased an SCT xCal2 with Extreme tunes from Eric at Innovative Diesel. World of difference in shifting and power!! Plus, with custome tunes, I got bigger injectors and a new turbo coming that a box can't account for. I love the SCT. New tunes for the turbo upgrade are going to be written by both Eric at Innovative (already have a rewritten tune waiting) and Matt at Spartan Diesel (purchased Turbo when he was with LIPD, but he's still gonna support me, now THAT is customer service!!).