[Rob@vividracing]

Cat bypass will be louder they are basically straight 3 inch downpipes. You can't get a more direct exhaust route than this. They are louder but not really terrible. Its noticeable but just gives the car a deep growl when you put your foot in it.

If this gives you any comfort my wife still likes the car.

With the renntech software you can use either the only reason you would need to run 200 cell cats would our fellow ca residents or other very strict emission states that actually look for cats.