EVO2 is all of it.I was thinking just the front booster to be honest, but having said that, I've no experience with the double booster arrangement. What is the deal with it? Assume stronger braking but no idea how it would fit. I've had many sets of rs33s but never taken the plunge for one reason or another (cowardice and cable run the two main ones), but have a set of tomacs I want to actually use.