Full exhaust system improve MPG? (Spintech)

[readyme]

I was told by my local shop that the best thing I could do was put in a full exhuast system. They are a SpinTech dealer, so that would be the system they would use. They custom bend all their pipe.
Is there really an added MPG gain with a full exhaust system?
What are your thoughts.
Thanks

[Jameslleary]

MAYBE 2 to 4 mpg.

[Low97tahoE]

i would say .5 to 1.5 depending on the truck....i got the .5......but i dont have headers yet so we'll see

[Tweaks]

I consistently return 1 mpg better than stock but in the case of my NBS, the headers don't have any reall effect on fuel economy and the only thing other than that in the system that isn't stock is my Corsa muffler. I had the same results with my previous Spintech single 3 inch cat-back setup with the pro-street muffler so it doesn't really matter between a full or cat-back system. Some even get worse gas mileage after a muffler or other exhaust mods because they can't seem to keep the right foot off of the accelerator.

[02LiftedSierra]

definitely not 2-4. 1 mpg max..and like tweaks said, if you keep your foot in it to hear the tone, you'll get worse.

[readyme]

Words can not describe how pissed I would be dropping $600+ on an exhaust and getting no return on MPG... I am not doing it for the sound or HP.... looks like I will pass since I am not planning any other mods.

[Mrs.Daigle]

because they can't seem to keep the right foot off of the accelerator.

^^^this is why my mileage didnt increase.....if you ask me its not worth it. Even if you did save at the max. 2-4 mpg it wont add up to the $600 you spent on the exhaust.

[Tweaks]

^^^this is why my mileage didnt increase.....if you ask me its not worth it. Even if you did save at the max. 2-4 mpg it wont add up to the $600 you spent on the exhaust.

Exactly^^^

Exhaust decisions and purchases should, in my humble opinion, never be made with the intent to gain fuel economy or put into the category of "this will pay for itself someday." A cheap muffler splice might pay for itself someday, but some 400 or more cat-back system definitely will not. In order to save gas, the computer needs to adjust and in such a way that it delivers less fuel to the engine over the course of a tank of gas. At the same time, the driver needs to drive like no alterations have been made, which is hard to do. Finally, the power gained needs to be down low in the rpm range so that the truck requires less fuel to accelerate from a stop or while merging onto a highway and often those gains are made in the mid to high rpms so when you put it all together, you can see why exhaust systems can never transform our trucks into a Prius. Buy it for looks, buy it for sound, but never buy exhaust with the intent of helping the U.S. import less oil ;)

[Low97tahoE]

Exactly^^^

Exhaust decisions and purchases should, in my humble opinion, never be made with the intent to gain fuel economy or put into the category of "this will pay for itself someday." A cheap muffler splice might pay for itself someday, but some 400 or more cat-back system definitely will not. In order to save gas, the computer needs to adjust and in such a way that it delivers less fuel to the engine over the course of a tank of gas. At the same time, the driver needs to drive like no alterations have been made, which is hard to do. Finally, the power gained needs to be down low in the rpm range so that the truck requires less fuel to accelerate from a stop or while merging onto a highway and often that gains are made in the mid to high rpms so when you put it all together, you can see why exhaust systems can never transform our trucks into a Prius. Buy it for looks, buy it for sound, but never buy exhaust with the intent of helpin the U.S. import less oil ;)

very well said.....agreed....with that said, i buy it for sound, don't look for much power from a simple muffler swap....as far as im concerned, the only part of an exhaust that makes any noticeable power gains is headers

[99chevy7.4L]

hey guys just a lil info. I put a Magnaflow 12468 underneath my dually. I had the 50 series flowmaster underneath it. I do notice with the magnaflow it does have more torque. It accelerates easier and quicker at lower RPM's. Keep in mind the flowmaster was dual 3 inch in and 3.5 inch out with x-pipe upstream from it. The magnaflow is a 2.5 inch Dual in and dual out. The magnaflow has an internal X-flow design. So the x-pipe that was in it is now gone. Thru my first tank of fuel I picked up roughly 1.4mpg. Whether or not its a fluke or not we'll see. But the big block is breathing alot better then it did.

[Tweaks]

hey guys just a lil info. I put a Magnaflow 12468 underneath my dually. I had the 50 series flowmaster underneath it. I do notice with the magnaflow it does have more torque. It accelerates easier and quicker at lower RPM's. Keep in mind the flowmaster was dual 3 inch in and 3.5 inch out with x-pipe upstream from it. The magnaflow is a 2.5 inch Dual in and dual out. The magnaflow has an internal X-flow design. So the x-pipe that was in it is now gone. Thru my first tank of fuel I picked up roughly 1.4mpg. Whether or not its a fluke or not we'll see. But the big block is breathing alot better then it did.

Anytime you ditch a Flowmaster and go with a superior product, especially one with a built in x-pipe, you're going to see things improve everywhere. I bet that increase won't be a fluke.

The sticker for my truck is 18mpg highway and I consistently return 19.5mpg combined city/highway these days. I want to say it's the corsa muffler but I also have a Blackbear tune so the two mods could be working together to improve my fuel economy.

[Cartman372]

Anytime you ditch a Flowmaster and go with a superior product, especially one with a built in x-pipe, you're going to see things improve everywhere. I bet that increase won't be a fluke.

The sticker for my truck is 18mpg highway and I consistently return 19.5mpg combined city/highway these days. I want to say it's the corsa muffler but I also have a Blackbear tune so the two mods could be working together to improve my fuel economy.

Well my 4DR 4WD Tahoe is supposed to get 15MPG Highway and I constantly return 20-21 highway

(Completely stock and 3.73 gears)

[Mrs.Daigle]

Well my 4DR 4WD Tahoe is supposed to get 15MPG Highway and I constantly return 20-21 highway

(Completely stock and 3.73 gears) you must be driving like miss daisy...because that's hard to achieve. Maybe it's just me though:burn::burn::burn:

[Cartman372]

you must be driving like miss daisy...because that's hard to achieve. Maybe it's just me though:burn::burn::burn:

Not at all. Was doing 75-80 the whole time with a lot of 3/4 throttle passing.

[Low97tahoE]

Anytime you ditch a Flowmaster and go with a superior product, especially one with a built in x-pipe, you're going to see things improve everywhere. I bet that increase won't be a fluke.

The sticker for my truck is 18mpg highway and I consistently return 19.5mpg combined city/highway these days. I want to say it's the corsa muffler but I also have a Blackbear tune so the two mods could be working together to improve my fuel economy.

agreed, you probably gained power because flowmaster is a loss in hp

[margaret]

hi guys apology for making up this thread but i just really need your help. i know this is too much (maybe) and i don't even know if this one is off topic but just wanna ask if where to buy a good full exhaust systems (http://www.racepages.com/auto/exhaust_emissions/complete_exhaust_system.html)? any help will do. thanks guys and apology again.

[Tweaks]

hi guys apology for making up this thread but i just really need your help. i know this is too much (maybe) and i don't even know if this one is off topic but just wanna ask if where to buy a good full exhaust systems (http://www.racepages.com/auto/exhaust_emissions/complete_exhaust_system.html)? any help will do. thanks guys and apology again.

We'd love to point you in the right direction, but we need so basic info first. What year, model, and engine? What sort of results are you after? What's the budget or amount of money you are willing to pour into this?

Just too many options available to even begin to mention which route to go but if we know what you are working with and what suits your style, we can help you out I'm sure.