Yesterday I put in a new muffler Magnaflow 12158 and it sound great. The only problem is I think it spends more gas now. Does anyone notice their gas milage go down after installing a new muffler? This would suck especially now with the gas priced right below $5 a gallon.

 

i know its very possible.

 

Are you sure you're not stomping on the gas pedal alot more now just to hear that sweet sound?

I know that would be my problem if I had an upgraded exhaust.

I've heard that it takes a while for a new muffler to settle (break in) which may be why the extra use of gas. Hopefully, someone who has upgraded their exhaust can attest to this.

 

my mpg only went up.. not by much though. but you shouldnt be loosing mpg..

 

I agree. I removed my rear cats and I think it slightly went up, not positive but it just appears to have.

 

i think you might be right about this becuase all day yesterday i had my radio off and windows open while i was listening to the great sound coming from the rear.

 

Installed the same muffler and am actually gettin 1mpg more than with the stock muffler, which doesn't make sense cuz I find myself in the throttle more just to hear that V6 groan !

I do try to keep it above 1800 rpm tho it sets up a harmonic inside the car that rivials the sub woofers behind the seats ! Other than that am well satisfied with the exhaust note.

Just my Dos Centavos !

 

I'm thinking of removing the back cats as well and was wondering if it really makes a difference in the sound and what is a decent cost for the removal if I take it to a shop.

 

has anybody done an emmisions test after the rear cats were removed?

 

Any pics after install, under car, I want to keep stock tips

 

Modifying your exhaust to cause your engine to breath easier, will do nothing but improve your performance, (and if you keep your foot out of it) increase your gas mileage.
You may lose a small amount of torque, but the engine should wind up faster and more than make up for it.

 

No, I just put Magnaflow catback Muffler 14805 on mine and actually getting about 2 to 3 more miles per gallon
depending on my driving

 

I found that the first tank was terrible for gas mileage, but I did have my foot in it, A LOT. lol After that, it slowly came up with each tank until it finally settled up a few points, just in time to install the sprint booster to put it back to where it was. lol

 

My muffler deletion yielded me over 31 mpg at 70-80 mph. I did however notice what I feel was a loss of low end torque but a gain in higher rpm power.

 

ok please explain what removing the rear cats will do to the xfire? i have a 2000 mustang gt full race bassanni exhaust n it sounds bad a$$., but on the x will it improve the sound with the stock muffler?

 

I had the rear cats removed last week and it sounds sweeeeet. Just be ready to go through a tank of gas much faster at first.

 

I have the magnaflow catback exhaust with the 14805 muffler and just took a 200 mile trip and got
28.57 mpg on the road, ave speed was between
65 & 100 mph. With the A/C on.

 

i just logged 29.2mpg today on my fillup. i've been doing alot of tire spinning and give it all it has take offs over the past week since my stepson is visiting and i'm showing off. i have now doubt i could have broke 31 not hot rodding. my first take i dropped to 26mpg. i have an aero turbine 2.5" muffler and a home made cold air setup.

 

20.5 MPG after the new Magnaflow and a Sprint booster install.

BUT, I don't think it's a fair time to judge!!!

I'm sure this is illegal somewhere!

Good lord this is fun!