2010 silverado

[bartjo06]

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.

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.

[Frenchy]

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