The only difference between a number 1 and 2-3 is the addition of a controller, and not only is a controller not needed, but a 2 stage number 1 could help an engine perform better then a number 2-3 by having a better range of flow when it's needed. This is because most people with number 2's use the boost to control flow, and they get the same flow no matter what rpm the engine is at. A number 1 can have 2 flows(if it has 2 stages) making the water/fuel ratio more consistent throughout the rpm range. If I were you, I'd get(or peice together) a number 1 with a dds3. It would cost about the same as a number two, could perform better then a number 2-3, and be safer.