2010 silverado

i have a 2010 silverado and i purchased a corsa exhaust system for it, had it installed and now the fuel mileage went down yes went down! the truck is new, has 4,000 miles on and i was getting 500 miles to the tank now down to 440. the exhaust is the sport tuned version and i just dont get it. i was told the mileage would get better because i drive slow no speeding,no hot rodding in this truck kid transporter. can anyone help me does it need to be tuned for the bigger exhaust? please help spent alot of money on this system.

get it tuned you might get your mileage back

are you sure you arent giving it more gas just to hear the exhaust? thats typically why people get worse mileage when they change the exhaust

If the catback has a large pipe and is free'r flowing it seems to me like it's going to lose MPG. Your truck is trying to make more hp with the free flowing exhaust. Get it tuned or at least scanned and see where the LTFT (long term fuel trim) is running now. Look at cars that get 40+ MPG, they have about a 1" exhaust pipe. :laugh:

The exhaust tone is very quiet, they made it so there is no drone on the inside of the truck. I wanted it loud but it did not turn out that way.

The stock exhaust is 3" from behind the cat to the muffler,and 2 3/4" out. That is strang to me, but on the corsa it is 3" all the way through. Like I said in my first post I don't get the RPM above 1,500 95% of the time.

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Originally Posted by RedHeartbeat

If the catback has a large pipe and is free'r flowing it seems to me like it's going to lose MPG. Your truck is trying to make more hp with the free flowing exhaust. Get it tuned or at least scanned and see where the LTFT (long term fuel trim) is running now. Look at cars that get 40+ MPG, they have about a 1" exhaust pipe. :laugh:

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Agreed. My 09's LTFT's were thrown way off after I put a CAI and exhaust on it. I'd log those and check them just to make sure, then have it tuned, the power and mpg increase you see with a tune will be well worth it IMO.

You change exhaust it's going to lean out the mixture, the truck will add more fuel. They're smart bastard these new ones.