As promised some piccies and explanation.
What I was aiming at was increase of area and actually some increase in pressure (velocity) due to maintained (roughly) cross sectional area after stream leaves nozzle.
Apologies for crappy quality of renderings due to lack of time...
It's only schematic for starters. Red stuff represents blocks base, blue are nozzles and greyish bits represent my 'innovation'.
TOP VIEW
LEVEL VIEW
Last One
The only problem is in manufactruing the damn thing. One could machine it form one piece of copper but costs probably would be greatly prohibitive. Then I thought about drilling hole for each pin. If nozzle is 1mm dia and is spaced by 2mm from each other then pins could be 2.5mm in dia if conoidal or 2.5 square base tapering to a point, which is much easier to make - just take 2.5mm dia hard copper or brass wire , grind it to shape leaving around 3mm for thread at one end, cut thread and screw it into ready threaded hole in baseplate.
What do you think?