Thats a interesting theory of getting black pipe of the same diameter to use as spraybar. Having said that, I am sure it would be ok to use as long as its a PVC type of plastic thats safe for aquarium use.
Pretty certain the pond section in LFS has various pipes of different diameters and lengths so should be something suitable. Or even a hardware store may have them but not sure if they have black pipes with matching diameter, worth a look anyhow.
Just need to drill suitable sized holes in a nice straight line and evenly spaced, easier said than done doing this for the first time, I have done this a couple times and its a bit of a faff sorting out a method for drilling these little holes.
I have still got my tetratec 1200 ex, a decent filter to be honest but i used the standard clear pipes that came with the filter, never thought of using black pipe to match black background at the time.