Topping induces stress, cutting out the little growth tips sets the plant behind. IMHO, you'd be better off LST'ing (low stress training). It is where you select the tops and branches that are growing ahead of the rest. Using a pinching maneuver, at the point you want the plant to be and squeeze the stalk, just enough that you feel it give between your fingers. Dont squeeze too hard. Then bend the branch or stalk, or stem over. If by chance you break the branch, just tape it with black electrical tape, just enough to hold the branch together, it WILL heal. You can do this many times keeping all the really fast growing tops and branches from getting ahead of most everything else. And nothing stops growing from cutting out the growth tips. There are a few videos on youtube about LST'ing. Bounce over and check em out.
Nim