Stop in for a cup of coffee

I did an exhaust system on an F250 with a 460 and now the customer is saying the gas mileage is in the toilet.

How does a truck go from 13 miles to the gallon with a plugged up, piece of trash, rusted exhaust to 7 miles to the gallon with a shiny new unrestricted flowmaster exhaust?????

Something wong


It is due to a big block truck that sounds good and goes better. Tell him to get his foot out of it.....