If I put a downpipe that is a cat delete on my car would it fail emissions?

 

Yes you can.

 

So it would fail emissions?

 

I think what he meant to say is yes you will fail emissions but you can fix that too.

Vagcom out the 02 sensor or put a spacer in the 02 sensor housing so it reads the proper range.

Do some searching and you will see plenty about how to work around the cat delete.