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Hi all. I've finally gotten my three main mods done. I wanted to report back on the 'butt dyno' and the MPG I'm getting on these. All of my MPG readings are based on driving 61mph on cruise control, no traffic. 8 miles out and 8 miles back. I reset the trip computer after the first 8 miles and averaged the two readings. I did this after each of the three changes.

First, I installed a Volant CAI. Very pleased with this one. I like the sound under acceleration, but notice very little to no difference in normal cruising/driving around town. The power increase was noticeable, but not alot. My impression is that the car just runs 'easier'. It feels more free. I'm sure I gained some HP. And that seems to be proven by the increase in my MPG. I started at 17.1MPG based on the car's trip computer. After the Volant, I went to 18.1MPG So I gained 1.0 MPG and can feel the increased power. A good mod.

Next, I bought a Superchips Cortex tuner. I've only tried one of the tunes so far. But this one was a 'wow'. I was surprised how much power I felt after the tune. Acceleration change was dramatic. I used the 'light tow' tune because I did not have 93 octane in the tank and read on the forums that the light tow tune (which only requires 91 octane) was very close to the 93 performance tune. The tune was an eye opener, in combination with the Volant CAI. Downside was I lost mpg. I had thought more HP would mean higher MPG, but not the case (at least with me). I went from 18.1MPg after the Volant, down to 17.0MPG most of the time to get that accelration. It really was a big difference. My wife drove it and came back and told me something was wrong with the car. She didn't know I had changed anything. She said the gas pedal was too touchy and she was jumping away from stoplights too quick! I love it! Thanks Superchips. I am going to try the economy 89 octane tune as well, and see what that does for my mpg.

Third change was adding a 22" Magnaflow muffler. Everyone was saying this will give me a few additional HP and TQ, so was expecting even more jump off the line. Well, I was shocked. I clearly lost torque and felt like just a touch less HP after getting up to speed. My MPG reading backs that up. I went from the 17.0 down to 16.9mpg. Just a small mpg change, but it felt exactly that way. A small loss of HP. The biggest change, though, was loss of low end torque. I'm bummed now. Feel like I spent money to lose power. Any suggestions on what I can do at this point? I thought about going back to the shop that did the install and seeing if there is anything they can recc changing.

BTW, the Magnaflow isn't too loud. Louder, but not bad. I've only ran the car up to 61mph but no drone at that point. I'll be traveling this w/e, so will see if I get any drone above 61mph.

All I can say is, do the Volant and the tune, but forget the Magnaflow muffler! I also called Magnaflow, but they had no suggestions. I told them it had been reported that on our vehicles a Magnaflow muffler should gain around 8HP. They said it was likely more like 3 or 4HP, so little that you'd never be able to feel the difference. But they did say it should be a slight gain, certainly not a loss of power. I'm real tempted to get the Magnaflow cut off and try a different muffler (anyone need a new 22" Magnaflow??... maybe you'll have better luck than I did with it). Maybe the Borla Pro XS? I'm all ears right now. Looking for suggestions to reverse what I've gotten from the Magnaflow. Heck, stock was better than what I've got now.
 

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so you are basing all this on butt dyno and MPG's? .1 MPG less could be from nothing more than being a little lead footed, or even brand of gas.....
 

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And you expect better fuel mileage with more power? it doesn't work like that. You get better fuel mileage when you have more airflow and your afr gets leaned out. or when you can use less of the accelerator pedal.
 

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Discussion Starter #4
All the factors were the same... same gas, same road, cruise sat at 61mph and no traffic at all, ran the road just before and just after the install, so nothing really changed as far as external factors.

But I agree, 0.1mpg could be anything. But it just backed up what I was feeling. As far as dyno, you can get some varied results from those too.
 

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Discussion Starter #6 (Edited)
As far as dyno, you can get some varied results from those too... one reason I felt a (reasonably) controlled test of mpg was a decent option.

From all I've read, you should get more HP with the muffler swap. And this can translate to better mpg IF you stay off of it. Doesn't an increase in HP mean less mashing on the pedal? At the least, I expected better airflow with the Magnaflow, hence leaner afr just as you say. So I should expect a bit better mpg. Or at least the same... certainly not worse. Even assuming mpg was the same (0.1mpg really isn't enough difference to really say, but clearly it did not go up), the loss of low end torque was very disappointing. My butt dyno is accurate enough to call that one for sure.
 

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The fuel economy is your foot! Drive the truck normal dude, and yes you can improve fuel economy with mods but most people cant keep there foot out of it!
 

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Discussion Starter #8
Fuel economy is not your foot when you have the cruise control sat and never touch the pedal.
 

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Discussion Starter #9
BTW, yeah sure, I'd like better fuel economy. Wouldn't we all. But I'm testing mpg here to see how that might reflect increased HP gains from the mods. That's the reason I used the light tow tune instead of the Mileage + tune (or whatever Superchips calls their mileage tune).
 

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jb2c, what model year is your Titan and what was the install method for the 22" Magnaflow.
 

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Ok so now we can use our cruise control to take off with? :huh:
Horsepower on the side of the box is BS! If it says 8hp its prob .8!
You also need to average fuel economy over a couple tanks of fuel! these truck are pig rich from the factory, thats why the fuel economy isnt all that great! Goodluck and Happy Modding
 

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I prefer butt dyno readings, because it's usually based on street driving. If the trucks feels slower on the street, I won't enjoy driving it as much, even if it's faster at the track.
 

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I am not buying for 1 second a Magnaflow doesn't flow more than the crappy OE muffler. The .1 difference in mpg could have been a ever so slightly headwind. 16 miles is not a long enough test for any type of mpg or mod. You need to let it learn for a week or so. My truck lost no low end tq and picked up a LOT every where and I can assure you that my exhaust system flowed significantly more than stock and prolly more than every other member's exhaust setup has/does. I had the fastest minor bolt-on Titan and it was a one tire fire, heavy, long bed. So trust me......give it some more time. The ecu needs to learn the mods and you need to use a longer trip under the exact same conditions (wind, temp, humidity, baro. pressure) to make an accurate comparison.
 
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I am not buying for 1 second a Magnaflow doesn't flow more than the crappy OE muffler. The .1 difference in mpg could have been a ever so slightly headwind. 16 miles is not a long enough test for any type of mpg or mod. You need to let it learn for a week or so. My truck lost no low end tq and picked up a LOT every where and I can assure you that my exhaust system flowed significantly more than stock and prolly more than every other member's exhaust setup has/does. I had the fastest minor bolt-on Titan and it was a one tire fire, heavy, long bed. So trust me......give it some more time. The ecu needs to learn the mods and you need to use a longer trip under the exact same conditions (wind, temp, humidity, baro. pressure) to make an accurate comparison.
Absolutely.

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Trust me you gained HP/TQ with the magnaflow. I gained .4 in the 1/4 mile with a Y pipe and 14" maggy. Don't start bashing magnaflow and get people thinking they suck. There is a guy over at club titan who couldn't break into the 13's for the life of him running spintec mufflers. He put on dual magnaflows and ran a 13.7, so trust me they outflow any other muffler on the market other than bullets or any other straight through design.
 

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Discussion Starter #17
First, I need to apologize... I have a QX56, not a Titan. I posted over on Club Armada first, and should have thought when I put the post up here to note what I had. But the engines are the same, and usually the results of mods are too. But my bad. It's a 2008 QX56.

No, we can't use cruise control to take off. But I didn't set the trip computer until after I was at cruise speed of 61mph. Each and every time. The 8HP gain was not on the box. It's what one of the guys who tested several different systems came up with for gain with the Magnaflow muffler. No idea if he is right or wrong, and Magnaflow thought 8HP was too high, but he seems to know pretty well what he's talking about and that was his actual dyno result. I didn't specifically expect to gain 8HP, but I sure didn't expect to lose any either.

Agreed that I need to check mpg over a longer distance. No doubt. I'm sure it will adjust somewhat. But this was all I could manage given my time limits. And I accounted for headwinds by driving it both directions and averaging the two numbers. That also accounted for any slight variation in grade as well. It was not any variation in conditions that changed any of my mpg numbers.

But the biggest thing here is that I guess I jumped the gun. I was so disappointed by not feeling an improvement and seeing an increase (even slight one) in mpg that I jumped to conclusion. I had not thought at all about the ECM needing to learn the change. I'm out of town this w/e and hopefully that will be enough driving to see an improvement. I know what my mpg was on a road trip before any mods. So I'll check it again this w/e.

Also, it's been pouring down rain all day here (guess this is the blizzard you guys to the north and west of North Carolina saw) so I haven't been able to go out and check on the install job the shop did. I need to see that before I say anything more. I wouldn't expect so, but a sloppy install job could also be the reason.

Everything I've read prior to buying says the Magnaflow should show me an increase in power. So I agree with what you guys are saying. I didn't buy the Magnaflow without doing my research. Just major disappointed today. And talking with Magnaflow didn't help matters any. I should have thought of the ECM and given it some drive time before commenting. I was just so excited to get the gains from the Volant and the tune, then to lose some of it with the muffler was a shock. We'll see.
 

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I know when i installed my FM i def felt a change in the throttle, with the stock it was stiffer on the accelerator, now its easier to get to the floor, but no HP loss :p, maybe thats what you felt?
 

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"IMO", the best way to gauge street results, is to have the ECU learn the changes for 600 miles, and to do several back-to-back 0-60s/1/4mi times with a Gtech, etc etc... Do that for every mod you add, average it, and those results would be more accurate.
 

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I'm gonna try and take a shot at explaining this. With the cruise control set at 61, you are most likely one in a specific RPM range. Let's say it's 1600-1800 rpm. We all know the 5.6 is finicky when it comes to exhaust. Too big piping and we lose loads of torque down low. Too small and we lose HP up top. By changing your exhaust, I'm guessing you lost low RPM torque, but gained HP up top. Since you weren't in the RPM region where you gained power, your engine had to work harder with that particular mod. Thus, your MPG suffered. You would've had to log throttle position or vacuum to see the difference in how hard the engine was having to work.
 
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