I will have ceramic coated headers and no turbo naturally aspirated mild built 351There's other factors to think about. We kinda need to tailor them to our own cars. For example, non coated headers get hot as hell under the hood. A big turbo can add underhood heat, changed to our radiators/cooling/fan/air deflectors, etc. That's why I dismiss a blanket 5* difference without knowing the parameters from a company trying to sell a kit with an underhood filter.