First and formost what trans are we talking about here? GM's TH400 you could run freakin rhino piss in and it'll be fine, fords require the heavier Type F fluid, and Chryslers, especially the newer ones, you run EXACTLY what they say or else. Basicly what B&M's trick shift is is Fords Type F. It's a heavier fluid to it makes transmissions shift firmer, which is actually better for the clutches, I'd also reccomend if you don't already have one, an aux trans cooler after the radiator. All the cooler in the radiator does is warm the fluid, it's actually warmer than is best for the trans after it's cooled. The best and correct way to do it is a new valve body, second would be a shift kit. If it's a newer computer controlled jobbie a reflash will up the line pressure, creating more heat, here's where the aux cooler comes in, but will give firmer shifts. And if you do ha e a computer controlled trans you should use the reccommended fluid or risk trans damage. If you do run it and it is safe, it'll shift firmer for a while but eventually the computer will adjust and compensate by increasing the engage times, and wearing out the clutch packs sooner. Hope that helps