Firstly your solution was not changing the pipes. You've wasted your money on pipes.
Listen to me:
Whenever you install a new pump and the steering gearbox takes some air in, it starts Giving whistle sound.
You just have to get a extra bottle of power fluid.
Tell mechanic to bleed some fluid out. With that bleeding there won't be no air in it.
I have been working on swaps from a long while. And whenever I've installed a new steering, this has happened or I've changed pump, this has happened.
So it was very simple.
And remember always take at least 3-4 advices and then go for that work.
Some people do not know themselves about these stuff and they come and misguide others by just shedding there inexperienced knowledge.
So you can ask anyone, whistle sound is affiliated by air thing.