Flowmaster 40 and mpg

[Ozraptor]

Hello forum, 3 month Raptor owner here. Wondering if anyone knows why before I got the flowmaster 40 mufflers I was getting 12.2 mpg and now I am getting 11.5? Am I suppose to get a tune after the muffler change? BTW, for people who are considering flowmaster 40, the sound is great from "outside " but the drone is extremely annoying. I do a lot of driving and Bluetooth phone calls and it is starting to get on my nerves. Always feel like i am yelling in my car. I am going to keep it as long as I can ,but I do want to switch it out to something as loud but less drone.

 

[Deinonychus]

Some resonator tips will help the drone some.

Considering break-in period, I'd have thought you mpg would have improved a little after 1000 miles or so.

Don't know about the tune.

 

[Dkyacht]

Simple answer. It's sounds much better so your on the gas more which = lower mpg.

Dave

 

[treypal]

hate the drone. Had to replace mine with a magnaflow.

 

[HSDMORGAN]

hate the drone. Had to replace mine with a magnaflow.

How do you lie the Magnaflow?

 

[treypal]

How do you lie the Magnaflow?

MUCH better, still sounds badass, but not nearly as much drone. I have turndowns which magnifies the drone problem.

 

[Reptar]

flowmasters are notorious on the 5.4 Lightnings/Harley trucks to rob power, and have horrific drone. Doesn't surprise me 1 bit the 6.2 is similar.

Your mileage probably went down from romping on the gas a bit more with the new exhaust, but it could also be from the power sucking nature of the chambered flowjunk. They may have been the ******* during the pushrod era, but now days a straight through design magnaflow, roush, sw, etc. is the way to go. Excellent sound, deep tone, very little to no drone, and no robbing power.

I did the roush catback on mine and I immediately went from 14.5 mpg to 12.5 mpg lol. After a few tanks it went back up though, I'm getting 14.5 again now that I'm not romping it more than usual since I'm used to the exhaust lol.

 

[Mitch12]

I have that same set up on my 6.2L. I took out the resonator and put in the 44 (basically exactly the same as the 40) with single in and dual out. I haven't seen any noticeable mpg changes expect for the fact that I slam on the gas to hear that baby purr. Also I have no drone until I hit 75-80. Then if I'm on the phone the caller usually tells me they can hear some background noise. But other than over 75 I don't really have a problem with drone

 

[Ozraptor]

MUCH better, still sounds badass, but not nearly as much drone. I have turndowns which magnifies the drone problem.

Magnaflow is not as loud as flowmaster right? I wanted to go with magna but heard too many people say that its barely louder than stock.

 

[Reptar]

Go roush, you won't be disappointed!

Loud outside, just right inside, quiet enough to hold a conversation, not affect phone calls, and not get annoying, loud enough to know the exhaust is there, and zero drone.