I took a few mins today and put the diablo tune (and trans tune) on and drove it around a bit. It felt a bit sluggish compared to the hemifever tune, but way batter than stock. I then put the hemifever tune back on and it felt a lot more lively. If you invest in the diablo, it's probably worth it (IMHO) to invest in the HF tune too. FWIW, my wife drove quite a bit with the diablo tune and never noticed much. With the HF tune on she just came back home a bit angry because she kept chirping the tires.