My Gen 3 Prius has a Gen 2 catalytic converter

How can you be sure it’s for a gen 2? What cooling lines would go to a hot exhaust?

 

If they bypassed the heat exchanger it should not pass the Visual part of the smog Inspection.

In California anyways that is part of the inspection. A lot of technicians don’t look under the car. Also if it has a magna flow converter on it for a gen 2 Then it should fail as modified.

to answer your uncertainty about if it is a GEN two cat or GEN three cat there should be a CO number on the Cadillac converter. You can look that number up it will tell you what years that converter goes on.

If a dealer truly did the work then they can be held responsible.

 

I believe an exception was made to use the Magna Flow as an approved replacement when Toyota didn't have any inventory

 

They are not coolant lines that "cool" anything. They are part of the exhaust pre-heater that provides faster warm up of the engine. Deleteig them means slower warm ups and decreased gas mileage, that's all. That should not be that great of an issue unless you are in a northern clime.

 

Basically the car will take longer to warm up without the stock exhaust (with it's exhaust heat-recovery system). During warm-up with the stock exhaust the car's (cold) coolant is run through a (warmer) radiator of some sort in the exhaust system, to accelerate coolant warm-up. Once the coolant temp risen, this diversion of coolant flow through the exhaust is stopped.

 

You might see lower MPG on the shortest of trips due to lengthened warm-up, and the heat/defrost won't be as forthcoming in winter- but in Arizona I don't think this is going to hit you that hard. Sounds like a fair swap.