How does the sound of these compare to stock cats? I want to make my car louder while being legal in VA and do I need a tune to run these? Also whats the difference between these and the 3 inch outlet ones?
These will allow more volume over factory cats as they flow much more efficiently. As for a tune being required, if used on an 05+ Mustang, a custom tune is recommended. The factory piping was 2.5 inches in diameter and if you are putting these on your factory mid pipe, these will be easier to install.