Two things: to achieve a "punch" you're going to need a tight loop, period. Get that right, and then work on poking that tighter loop (which also will most likely have increased line speed) where you need it.
Another matter to consider is your fly, particularly its specific combination of weight and aerodynamics. A 3wt isn't ideal for flies with much weight or bulk, due to the reduced power of a light line to turn a fly over. However, a fly with the right combo of weight and size could help.
For example, last friday I was fishing my 3wt and throwing a variety of flies, many of which are thought of as being too large for a 3wt. A brass eyed size 6 clouser was tough to cast far due to its weight and a tendency to drop on the back cast, and a size 6 popper with a cupped face was tough to cast over 30' due to poor aerodynamics. However, I was quite pleased with how well a size 6 bendback cast. It had just the right combination of weight and profile to cast REALLY well on such a light rod, which is nice considering it was about 2" long.
The bendback was similar to these, except tied on a size 6 34011 hook, without lead on the shank, and with prism eyes instead of doll eyes-