dual exhaust

yolo2rv · 03-07-2015, 06:52 PM

what would I gain If I replaced the factory exhaust on a 2014 6.0L Silverado with dual exhaust? I'm not talking from the mufflers back, but from the exhaust manifolds. Would HP increase and by how much? Would fuel mileage increase and approx. by how much? Would it void the warranty? Would the cost of installing it be offset by the possible savings?

**chuckster57** · 03-07-2015, 07:26 PM

I'm not an engineer, but having wrenched on auto's for the last 40+ years, I can say that the newer computer controlled gasoline engines are about as efficient and powerful as they can be with the factory exhaust/intake.

With that said, you will probably void the factory warranty if you modify/alter the exhaust system. Mileage/HP gains are better achieved with "programming" these days.

master sprinter · 03-07-2015, 07:31 PM

Probably would not be a true dual exhaust as todays vehicles have a catalytic convertor and sometimes multiple oxygen sensors in the exhaust. These cannot be removed or is expensive to remove if possible at all. In Ontario you also have to pass emissions which would probably not be possible after conversion, as well as fighting ECM faults, poor milage due to tampering with it.

Some exhaust tweaking can be done, but chipping it would probably give more performance gain or combination of chipping, exhaust and intake mods.

Desert185 · 03-07-2015, 09:42 PM

Look into a Magnaflow cat back system. It is possible to realize some gains with a less restrictive muffler and mandrel bent pipe(s). The same can be said for a less restrictive cold air intake system. The dyno doesn't lie.

Whether the money spent will justify any performance or mileage gains is for you to decide.

Larry1013 · 03-08-2015, 02:29 AM

I would say you would cause more headaches and CEL's than mpg gained on the newer vehicles outside of warranty problems down the road.

On an old 1996 F350 7.3L diesel, I actually lost 1-2mpg by going from the stock exhaust with catalytic convertor system to a 4" turbo to rear wheels system less catalytic convertor.

notanlines · 03-08-2015, 02:45 AM

Yolo, don't you think GM engineers have given a little thought to the best ways to get the best mileage possible on your truck? They are in a fight for their lives with Ford and Dodge over the mileage/load/horsepower crown. A little think like dual exhaust wouldn't have stopped them if it made a difference. Do you mind if I ask what your mileage is and why are you not satisfied with it....

jsmith948 · 03-08-2015, 03:52 AM

Have to agree with Chuckster, the modern computerized motors rely on sensors in the exhaust and intake. IMO, leave it stock.

ncgrl1 · 03-08-2015, 07:00 AM

You will actually lose low end torque which is where you need it for towing. You would gain power on the higher rpm's where you don't normally run.
With performance mods you typically gain on one end, and lose on the other.
You just have to decide which one meets your needs.

Bbfd · 03-08-2015, 07:43 AM

Quote:

Originally Posted by master sprinter

Some exhaust tweaking can be done, but chipping it would probably give more performance gain or combination of chipping, exhaust and intake mods.

I have been toying with the idea of picking up a slightly used Camaro and have been doing some reading on easy tweaks. What I have seen says low restriction air intake, chip and headers give the most bang for the buck. Article said cat back exhaust did not give much benefit the cost. Not sure how true it is so if I were the OP I would do a bit more research to see what mods will help the most with altering towing characteristics if that is important.

yolo2rv · 03-08-2015, 09:42 AM

General consensus seems to be leave it stock to avoid problems.

Notanlines: we get average 8 mpg at or near 60mph. The truck meets our expectations and we're very satisfied with it's performance. If we could improve on it we'd be open to suggestions.

Thank-you all for responding, safe travels.

Desert185 · 03-08-2015, 10:07 AM

Quote:

Originally Posted by yolo2rv

General consensus seems to be leave it stock to avoid problems.

Thank-you all for responding, safe travels.

General consensus also elects politicians who don't always act in the best interest of the people who elected them. Do the research and decide what is best for your particular circumstance. Physics are physics, and dyno's don't lie.

**sourdough** · 03-08-2015, 11:33 AM

Cat back systems don't do much. Mine made the exhaust sound louder but didn't do anything appreciable for performance. Cold air intakes are the same. They cost $300+, make your engine much louder under load and don't do anything appreciable for performance. In both cases, to me, it was a waste, factoring in cost, performance gains or lack thereof and negatives such as increased noise. I pulled the cold air intake off after about 6 mos.; it's still in the attic.

With modern engines and the complexity of the computers which run them, and the efficiency they provide, a person is hard pressed to make add ons that will do anything appreciable. If you don't like the performance of your engine I would just order a high performance crate engine and drop it in................

bsmith0404 · 03-08-2015, 07:05 PM

I had a cold air intake and cat back system on my 6.0...did nothing for me, got the same fuel mileage you are getting. There are several tests you can find on-line that show the best air cleaner for the GM trucks is the AC Delco. It flows great, and filters better than just about everything out there. As for the exhaust, you can probably see some gains with a full dual run, the O2 sensors are all in the down pipes and can be replaced in any dual system so it will not affect the computer and how it manages your air fuel mixture. They have to be set up that way so it knows what side is running rich or lean. The best systems have always run dual cats with an X or H pipe to balance the exhaust flow/pressure. However, as already mentioned, the performance gains are mainly on the top end of the RPM range, not on your low end torque range. Personally, anything you do will most likely lead to disappointment as far as bang for buck.

As for the warranty, exhaust modifications WILL NOT void your warranty. The law states that in order for a company to deny a warranty claim due to modifications, THEY have to PROVE the claim was CAUSED by the modification. I can't see any company being able to prove damage caused by a better flowing exhaust system. Of course that is assuming you don't start eliminating essential components such as O2 sensors.

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