1sicss

iTrader: (3)

So first off I know this is probably the wrong place to ask, but here it goes. I have a 2004 Denali 6.0L I already have a CAI on it and this thing gets horrible gas mileage. I was wondering if adding a catback exhaust would help out mpg's. On top of that saying if I put on a catback then shorty headers would that further improve MPG's or hurt MPG's let me know what you think.

Zlow28

iTrader: (11)

a catback might get you a mpg or two. Mods that give you better airflow or decrease heat in the car, will help mpg because your making the engine run smoother.

Cams and mods that require more fuel, will drop your mpg.

1sicss

iTrader: (3)

So on these computer driven cars will the ecm,pcm whatever it is, dump more fuel due to increase of power from headers and catback. If not I will do both, if it does just might do a catback and that is it.

00ZNewb

iTrader: (2)

The best way to get mileage from anything is going to be in how you drive it. Next time you fill up, force yourself to NEVER let the engine go over 2k rpm. And that means you have to drive 60 mph everywhere. Drive out half a tank, then refill and check your mileage. Other than that, make sure you have good plugs, and O2 sensors with a clean air filter and tire pressure correct. You wont ever see 20+ mpg in almost any truck. Baby it around and you might see 18-19.

Blackpanther99

iTrader: (8)

Its gonna be a tough one to be over 20mpg since its a pretty big motor on a heavy truck.

z28SSilvest

Might as well get a catback to enjoy the sound of a 6.0L drinking gas like its water

omarrakeen

iTrader: (2)

LOL that is harsh. OP mods wont give you that huge MPG gain. you probably wont even notice it..if you're spending 1K+ for mods just to get 1 or 2 mpg might as well spend them on gas..

Hamrdown

iTrader: (25)

Don't get shorty headers! They're worthless when a full length header is available. If your only choice is stock or shorties then stay stock & save your money. A catback,deleted cats if you can, and tune for mileage would be your best bet as long as you can keep your foot out if it. But really that'll only help highway mileage mostly. If your looking for in town mileage put steeper gears in the rear to help get that pig moving...or buy a better fuel economy vehicle haha.