Flowmaster 40 series bad for the engine?

I want to add a flowmaster 40 series to my dads 2001 chevy silverado, will it make the engine less effiecent or worse on gas? If so is there any other ways i can make the truck sound pretty loud?|||If anything, it ought to improve fuel economy somewhat because you will be reducing exhaust backpressure.|||Mufflers can do no harm to an engine assuming they have an outlet which a flowmaster 40 series would have of course.





If you want a louder car flowmasters will do that, intakes are the other big way to make more engine noise. In my car there are 2 resonators in the stock intake, one located after the airbox and one before it. By simply removing the air box and putting a cone air filter on the car I easily made my car a good bit louder and possibly faster and more fuel efficient. I later added an unresonated metal intake tube which again made the car a little louder.|||It might actually increase the fuel efficiency slightly as it flows more freely reducing back pressure and increasing horse power.|||no,not bad good..