Restriction of Legalization?

Legalization obviously says CATO, that is if we want to add $180 billion to the US economy:

As Congress prepares to tackle immigration reform, a new study from the Cato Institute estimates that the difference in the impact on U.S. households between the most and least restrictive policies would be about a quarter of a trillion dollars. Using a model of the U.S. economy developed for the Department of Homeland Security and other U.S. agencies, economists Peter Dixon and Maureen Rimmer conclude that increased restriction of illegal immigration would cost U.S. households $80 billion a year, while legalization through a temporary visa program would raise incomes by $180 billion.