Will just swapping out the factory muffler for a flow series 50 or maggie 18" increase my gas milage?? Dont have the money for high flow cats and a cat back so I want to start somewhere. Any thoughts woudl be helpful

 

You wont see a fuel economy increase with a performance muffler. If anything, you might see a drop in MPG because you will be driving more aggressively so you can hear your exhaust.

 

Yep, the ugly side of exhaust. You keep your foot in the throttle to hear the exhaust, so you mileage goes down.

 

Seriously, you wouldn't see any increase in fuel efficiency? It was my understanding that changing to a high flow muffler would increase your gas mileage because it would decrease back pressure. I would love to hear other peoples take on this because this is a relatively cheap mod to do.

 

From what I understand, less backpressure actually hurts your milage because the engine doesnt scavange as much.
Look at it this way: if you modify the intake or exhaust to get more flow, the computer has no choice but to feed more fuel to the engine to keep the air/fuel mix from going too lean. That will reduce your milage.
Ive heard some people claim that intake and exhaust mods will improve your milage because it makes the engine put out more power, so it doesnt have to work as hard, but Ive never seen that happen.

 

The gains that you see are very minimal at best. Plus, until the new wears off you will accelerate faster and keep your foot in it longer just to hear the rumble. I've had my Magnaflow + high flows for about 9 months and I still haven't noticed any increase is mpgs. However, I also still drive it like I stole it.

 

I have been running my exhaust for about 17 months, the Edge Evo for about 16 months, the intake for about 1 year, and the bed cover for about 1 year. Out of all of them the only one that has had any effect on my mileage was the Edge Evo running level 3 with custom settings and 93 oct gas I was avg about 2 mpg better than stock. Even though each one of the other mods claims it increase your mileage, atleast for me they didn't. Or if they did it wasn't enough to really make me notice the differance, maybe .1-.3 mpg at most. But lucky for me I didn't buy ANY of them to increase my mileage.

 

less back press ure hurts mileage?not- less velocity hurts mileage-if you ever researched gas combustion engines or studied air flow in general- you will see this-phil

 

First mod I did on my truck was a Borla SI/SO cat-back. I gained 1.8 mpg on the highway. I don't bother with figuring city driving as it's gonna be dismal no matter what.

That 1.8 mpg gain has been consistent even after adding an AF1 intake.

If you'll look at most cat-back manufacturer's sites they will claim about 1 - 3 mpg gains.

So, yes, an aftermarket cat-back system (well, most of them) should show a small increase in mpg.

 

But they'll still claim its all about the back pressure...

 

I gained about 1.5 MPG with my Magnaflow. Gained nothing with Flows on a previous truck.