What is the purpose of the Crossover pipe?

[Pasteurised]

Always wondered why the turbo intake is routed over the top of the engine as standard.

Seems the most common/first mod anyone with these engines does is a crossover delete.

[willisit]

No idea, but in the C20LET the pipe ran in front and was prone to collapsing. Perhaps it's emissions related (heat etc).

[Crafty_]

Z20LET had it too.

Not really sure why they decided to do it that way. As suggested maybe they were concerned with hoses collapsing or it was a induction noise thing ?

As you say, some people use the diesel airbox that has front exit, like this