I have been driving a 2002 Firehawk---6 speed for the last 3 weeks and only averaging 20 mpg per tank---79 mph down interstate. The car has QTP long tube headers----3 inch dual exhaust---NGK V power Racing #8 plugs gapped at .030. I think its the wrong plug to get decent gas mileage.
If I change to a TR55 and gap them at .050, will that help mileage?