My truck is diablo tuned and it did add a little HP from what i "felt." i havent been able to dyno the changes but im sure its not much. That being said, i paid $350 for the tuner. If you want to have you truck "custom" diablo tuned you have to buy the $175 cable and pay another $200 to have a "generic" tune. If i could go back i would have went with a Black bear or wheatly tune. Theres not alot to adjust and its a pain in the *** to read on the little screen, kinda forcing you to get the PC cable. The only upside i see is that you can read/clear codes. So the bottom line is.... yes, the diablo does work, is it great? kinda. Does it compete with a custom tune in HP/dollar? No way. A BB tune is I think $250 for him to come to you.