Tetratec EX2400 spraybar works perfectly.
....
Thanks Wallace, hunting this set down looks like it might be tricky due to the age of the original filter. It's a simple option though
Area is
View attachment 79233
So 25mm is 3.14 x (12.5)^2 = 490mm2
and 16mm is 3.14 x ( 8)^2 = 201.
So forcing 25mm diameter into 2 off 16mm diameter is a 20% reduction in area (and flow).
You will also have a balancing issues with two bars, in that the flow will tend to take the easiest route and you will get dissimilar flows made even worse by the "slow" one accumulating detritus slowing flow even more.