Bad mileage with 5" turbo-back exhaust?

[BigChad]

Have any of you experienced worse fuel mileage with 5" exhaust as opposed to say, 4"? I went from stock 3.5" to 5" straight piped, and added an edge tuner (on economy tune), and my mileage has not gotten any better, maybe a little worse. Is my 5" too much free flow? I love the look and sound, and my egt's are great!

I tuned the truck back to stock and still didn't get any better, so I don't think the tuner is the problem.

My truck is a 2007 F250, 6.0, with the bulletproofing mods as well.

[331stroker]

I have a 5" on my 06 with a custom SRL tune from Matt at gearhead and when I have actually gotten much better milage. Might want to try custom tunes...

[BigChad]

Thanks for the tip, I assume he could give me a custom tune to use with my current programmer? I'm using an Edge CTS. I'll give him a call tomorrow.

[pizza pig]

You're not going to lose mpg with a 5" exhaust its an myth... you dont need any back pressure on a diesel...

Hate to break it to you, but no you cant get tunes from Matt you need an SCT to use anyones tunes like matts, erics etc..

However if your CTS is an Evolution model you can send it to Bill at PHP and he can convert it to a gryphon and he can set up a custom tune for your edge.

[DSTRBD]

As previously stated, no back pressure is necessary. An exhaust will not cause your mileage to go down. However, your right foot might be if you are driving aggressively.