cat back and fuel consumption

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Sierra_411

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Helloo everyone

I have installed borla cat back system and i have noticed that fuel consumption increased is it normal or there is something wrong in installation note that there is no air leackage in the pipe.
vehicle : sierra 2012
engine : 5.3 litres

waiting for your feedback

thanks
 
I would agree with happy, weather knowingly or not, installing the loud exhaust has caused you to drive more aggressively to get off on hearing the noise.

If you want to further reduce it more, add big tires, cold air intake, K&N air filter etc. All these things will influence you to drive faster and use more fuel.

If a Borla exhaust, K&N filter, cold air intake etc got better mileage for these trucks you can bet your life GM would be putting them on at the factory because the gov't is making them improve mileage and if it worked, they could save million if not billions in reseach. Thing is, it does not give you better mileage, its all hype promoted by the after-market companies looking to cash in on the fad.

Don't get me wrong. Not saying they don't increase HP, saying increasing gas mileage in a mass air flow computer controlled system in not possible with this stuff. Thats like saying your computer will run faster in you hook up a bigger monitor and open the windows.
 
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on my 98 i put shortys, flowmaster,3inch exhaust,k&n
there wasn't any noticable fuel inprovement
but there was a inprovement in power
it was noticable when towing my camper trailer
i did the mods in hopes of fuel inprovement, with no luck
 
1996 (OBDII) up are controlled by the computer. Engine modifications related to air are not going to improve mileage. The computer uses a Mass Air Flow Sensor to determine the amount of air coming in and the amount of fuel needed to meet the air/fuel ratio, and adjusts the fuel to meet that air. The air to fuel ratio is set at 14.7 lbs of air to 1 pound of fuel (measure in Mass) and programmed in the power train control module. So when the engine takes in more air, the computer compensates by adding more fuel at the programmed ratio. You can not force in more air and have the computer use less fuel, which is what has to occur to get better mileage.

I know there is a lot of hype out there about products that save fuel, people tout huge mpg gains on forums by adding cold air intakes, dual exhaust etc but its all anecdotal, meaning is only opinion not based on facts. In other words, BS.

Also many acquaint noise to mean more power and thats what these after-markets producers of cold air intakes, low restriction air filters and exhaust components count on to sell their products. Sure they make more hp but at what rpm and at what cost. The average person cannot tell a 10-20 hp increase in his motor, its the loud noise that gives him that feeling of more HP. So whats the point really but to relieve you of your hard earned $.
 
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I own a 1992 Sierra with a 5.0L. I was wanting to add a dual exhaust system. I cannot find one online so I went to a custom exhaust shop. My question, should I go with magnaflow or flowmaster? Will I need to change my stock filter? Any recommendations would be very helpful, thank you.
 
I bought a 2004 GMC Sierra with 120000 miles on it with 4.8..only got 15-16 mpg...then put on performance muffler and K& N...went up to 20 and now I chipped it and up to 22 mpg and this is doing over 70 mph...oh I also took off those steel wheels and put on aluminium with same size height but wider tires.
 
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