Exhaust Mods; Increased MPG

[DirtyEC]

I thought I'd share this info. This past weekend I removed my catalytic converter (no inspection in my county) and muffler from my truck. It's a 2004 F350 CC 4X4 dually. It had an aftermarket 4" exhaust from the catalytic converter back to the tailpipe. It is 3.5" from the turbo to the cat. I unbolted the cat, and cut the inlet flange end off. I welded this flange end to a piece of 4" straight pipe I bought from a muffler shop. The straight pipe is 5 feet long. I turned it out in front of the rear tire at an angle. I used the piece of tail pipe that goes up and over the rear axle to make my 60 degree turn out in front of the tire. I welded it up, and put a 5" chrome tip on it for looks too.

I noticed that the hissing sound is a lot more pronounced now. It has a nice growl at low RPM too. At WOT it sounds like a damn beast.

My MPG increased too. From 14.5 to 16.5 in the city and from 16 to 19 on the highway.

[craftkr]

I've been wondering about the restriction the cat can cause, esp. with a high milage truck. We don't have emissions testting in this part of Texas, but I know it's a possibility in the futre. Guess I could just get the delete pipe and then throw the cat back on for inspections. But your increase in milage makes me think it's worth it. How many miles did your truck have on it?

[rebelranger]

I did the whole system for $219 turbo back offroad system no cat or muffler and only got a .5mpg increas so far.

[DirtyEC]

Originally Posted by craftkr

I've been wondering about the restriction the cat can cause, esp. with a high milage truck. We don't have emissions testting in this part of Texas, but I know it's a possibility in the futre. Guess I could just get the delete pipe and then throw the cat back on for inspections. But your increase in milage makes me think it's worth it. How many miles did your truck have on it?

My truck has 102,000 miles.

[DirtyEC]

Originally Posted by rebelranger

I did the whole system for $219 turbo back offroad system no cat or muffler and only got a .5mpg increas so far.

My cost was $76. I bought a 10 ft stick of 4" pipe from a muffler shop & did the work myself. It is not 4" from the turbo back though.

[DirtyEC]

Pics of the new exhaust.

[Ben27b]

Looks good

[PGreenSVT]

I have a hard time believing you got a 3mpg gain out of an exhaust system. I have a full 4" turbo back straight piped setup and saw zero mileage gains.

[Galaxie]

The people on this site talked me into removing my muffler. Thank god I did, it sounds so much better. My fuel milage went DOWN big time. But that is because I cant keep off of that skinny pedal. I will do a true mesure next tank tho!

[PGreenSVT]

Originally Posted by Galaxie

The people on this site talked me into removing my muffler. Thank god I did, it sounds so much better. My fuel milage went DOWN big time. But that is because I cant keep off of that skinny pedal. I will do a true mesure next tank tho!

Right there is the crux of the problem. Every thing I have done that should increase mileage has cost me mileage because my right foot refuses to listen to me. Then again what's the sense of beefing the thing up if you're not going to use it. These things don't like to be babied.