depends on ur car. a header back would be a great addition but if ur going to run cat(s) its going to rob u of power. if you dont run cats not only will it be cheaper but better gas mileage, but you will have a CEL. so...you have MANY different routes. You can get the CEL to go off with a tune but then again...your going to be spending right at 450 for everything or a lot more. sooo...you really got to figure out which route u want to go