I simply use it as a base comparision. Its data that I have, we'll call third party data. I know the results from the different components on that particular motor, and yes I know that the 5.0 and 4.6/5.4 are highly different. And yes I am one person, sharing my experiences trying different combinations in the hopes that someone can one up them and I can make mine better

 

On mine, I have the hedders followed by 3" true dual exhaust with the heddman X-pipe with 2 IMCO 1-chamber mufflers. I could see a difference in gas mileage.

 

On your what, F-150? I have a very similiar setup minus the headers, and using flowmaster 40 series