4.7 Magnaflow MPG Report

[12guns]

I've had my Magnaflow on for several days now. Just took a 90 mile round-trip on the interstate to see how my MPG was. Before I have hand calculated 17 mpg for a couple hundred miles on the interstate and a bit of in town driving. That was w/ the cruise set on 74. Keep in mind I have 6 ply semi agressive a/t tires.
Today I after driving w/ the cruise set on 71 I hand calculated 16.7!! And contrary to what others say the Magnaflow, routed to the right rear, IS much louder than stock and drones like crazy at the 2k rpm mark. What sucks is that is sounds awesome in town (even though it's still quite louder than stock), but when I'm on the highway the droning is the worst. I'll clean my K & N, mass airflow sensor, and reset the ECU. I'll have an update after the weekend w/ some more highway driving. If there's not an increase in MPG I'll be cutting this thing off and putting the stock back on. Which means, it'll be for sale cheap! On another thread they guy dumped his under the 4runner...correct me if I'm wrong, but routing to the back SHOULD be quieter, right? My other option is a CAI, but I'm not sure that will make enough difference to matter. Thoughts??

 

[Autbond]

I've had my Magnaflow on for several days now. Just took a 90 mile round-trip on the interstate to see how my MPG was. Before I have hand calculated 17 mpg for a couple hundred miles on the interstate and a bit of in town driving. That was w/ the cruise set on 74. Keep in mind I have 6 ply semi agressive a/t tires.
Today I after driving w/ the cruise set on 71 I hand calculated 16.7!! And contrary to what others say the Magnaflow, routed to the right rear, IS much louder than stock and drones like crazy at the 2k rpm mark. What sucks is that is sounds awesome in town (even though it's still quite louder than stock), but when I'm on the highway the droning is the worst. I'll clean my K & N, mass airflow sensor, and reset the ECU. I'll have an update after the weekend w/ some more highway driving. If there's not an increase in MPG I'll be cutting this thing off and putting the stock back on. Which means, it'll be for sale cheap! On another thread they guy dumped his under the 4runner...correct me if I'm wrong, but routing to the back SHOULD be quieter, right? My other option is a CAI, but I'm not sure that will make enough difference to matter. Thoughts??

I have my magnaflow turned down right after the muffler under the vehicle and it's not really that loud and I don't get any annoying droning. I cannot remember which muffler I got though, I will have to look

 

[12guns]

See which on you have if you don't mind.
Something else I thought of is that my opinion of "loud" may not be the same as another person who may have had pipes or other mufflers on their vehicles before. I've never had anything different than stock, so it's quite a difference for me. It's just the droning that bugs me, not to mention the apparent decrease in MPG.

 

[daPitbull]

Out of curiosity, can you measure the overall length of your magnaflow? Is it round or oval?

 

[Autbond]

Out of curiosity, can you measure the overall length of your magnaflow? Is it round or oval?

Yea I will when I am back at my house; my gas mileage went up also when I got it. On my f-150 I had a long time ago I had just exhaust and my mileage didn't really change at all but when I put a CAI on with the exhaust the mileage went down so.. if you have a cAI and the exhaust that may be why. All I have is a K&N drop in filter.

 

[12guns]

Mine is appx 13.5" x 9" oval. Looks small? Maybe I should have specified which one I wanted, but at the time I didn't know there were different size "universal" mufflers. Curious to see other's measurements.

 

[daPitbull]

I think thats where your problem is, mine is 18.5" overall length (oval). I had a 15" length on my FJ, and that was loud.

Mine is appx 13.5" x 9" oval. Looks small? Maybe I should have specified which one I wanted, but at the time I didn't know there were different size "universal" mufflers. Curious to see other's measurements.

 

[GRIMACE]

I can vouch for the increased gas mileage, plus the annoying drone with magnaflow catback. I'm very interested in this thread. If I can put an after market exhaust back on I'd love to do it. I'm curious why some people have drone and some do not.

So I just mount the muffler upside down?

12guns do you have V8?

 

[eskimochaos]

I can vouch for the increased gas mileage, plus the annoying drone with magnaflow catback. I'm very interested in this thread. If I can put an after market exhaust back on I'd love to do it. I'm curious why some people have drone and some do not.

So I just mount the muffler upside down?

12guns do you have V8?

"4.7 Magnaflow report"...................

 

[12guns]

Looks like I used a shorter magnaflow, different model number. I didn't know there were so many, I just asked the muffler shop if this was the "quieter" of the aftermarket exhausts, and he said yes. Based on what others are saying, the 18" long (vs. my 14") does not have the drone that I have, yet still sounds good when you stomp on it. I may be getting the longer one, depending on what I can work out w/ the muffler shop.

 

[4Runner8]

I think thats where your problem is, mine is 18.5" overall length (oval). I had a 15" length on my FJ, and that was loud.

yep, thats the 12256 (what i got, still waiting for it to arrive.) i beleive you got the small one 12guns. smaller = louder

you got the 11216.

 

[Autbond]

Mine is appx 13.5" x 9" oval. Looks small? Maybe I should have specified which one I wanted, but at the time I didn't know there were different size "universal" mufflers. Curious to see other's measurements.

I got the same measurements as you did. I don't know if the length of the pipe is making it louder for some reason? I wouldn't know why but obviously it is because mine is not loud at all. I don't get any drone, you can only really hear it around 2-4k rpm and even then I would compare it to maybe a little louder than a stock mustang gt.

 

[12guns]

yep, thats the 12256 (what i got, still waiting for it to arrive.) i beleive you got the small one 12guns. smaller = louder

you got the 11216.

Right you are. Not sure what I'm gonna do yet, but if my MPG stays lower than stock I'll be switching back. Wish I paid more attention to the part number the other guy used, but I thought the muffler shop would know better. Oh well, at least I'll only be out the labor to reinstall my OEM muffler. Maybe I can sell my Magnaflow and recoop some of those costs as well.

 

[Nuke]

Intersesting. And after over 30 years of maintaining detailed mileage records on over a dozen vehicles, I'll ask you to let us know what your results look like after about another 30-50 data points.

There are so many variables that can affect fuel mileage that you can take dozens of 400 mile trips on the same roads in the same car with the same load at the same speed with gas from the same stations and still get some rather widely varying data (I recently used to drive from Kentucky to Chicago and back every 2 weeks for 2 years). Also, I hope you're hand calculating instead of using the near-worthless on-board. It takes many data points to get anything meaningfull.

One of the biggest variables is the ethanol content of the fuel. That in itself can knock you down as much as 4 MPG or more from tank to tank.

 

[Autbond]

I totally agree about everything you said. There are a few local gas stations that sell 100% gasoline and i have definitely noticed a significant difference in mileage when I do fill up there. The computer is totally worthless, except I know when it says 0 till empty I have at least 30 miles before I run out, on the interstate.

 

[daPitbull]

Keep in mind this isn't a direct swap out. Stock muffler is offset/offset, #12256 is offset/center, so you'll need a new tailpipe. They do offer an offset/offset of the same dimensions as the #12256 but you'll have to look up the number.

yep, thats the 12256 (what i got, still waiting for it to arrive.) i beleive you got the small one 12guns. smaller = louder

you got the 11216.

 

[4Runner8]

Keep in mind this isn't a direct swap out. Stock muffler is offset/offset, #12256 is offset/center, so you'll need a new tailpipe. They do offer an offset/offset of the same dimensions as the #12256 but you'll have to look up the number.

yea i know but im dumping mine under the truck right after the muffler so it doesnt matter.

 

[Carl_G]

That drone you were talking about on the highway is EXACTLY what I experienced when I had a k & n CAI. It was unbearable. That's why I put the stock system back on and really enjoy the close to silent engine (v8)

 

[4Runner8]

just got my magnaflow delivered today. dapitbull i dont know about 08 models but my 03 will allow the use of stock piping as it is center into the muffler and offset out of the muffler. and magnaflows can be flipped for custom installs. if im not mistaken

 

[12guns]

No more Magnaflow

Friday I had my stock muffler put back on. I couldn't stand the drone at highway speeds. I thought about going to the longer Magnaflow, but decided I don't need to noise, I didn't see any gain in MPG, and I missed my quiet 4runner. He kept the old muffler to cover his labor to re install the factory muffler. I was happy enough. Oh, and I left my tailpipe routed to the side w/ no resonator and it sound about the same as stock. I can hear a touch more noise at 2k rpm, but any a/t tire noise is louder than the muffler.