I've never used molasses so I can't really comment on it.
I use Canna PK in the middle of flower which will increase bud size.
A lot has to do with strain as well.
I recommend only topping once and do it as early as possble.
Try and leave yourself 4 nodes when you do.
You should then end up with 8 or so thick braches = 8 big fat colas.