Hey guys. Recently bought an 09 Chevy 2500. It's all pretty well stock w the exception of having the dpf deleted. I'm getting pretty terrible mileage. 14.6mpg empty on the freeway, and around 10.5 towing around 5k. It runs and drives well for how many miles are on it, just bad mileage. I guess my question is could the previous owner have done the delete without properly programming the ecm? There is no physical tuner in the truck, and it feels pretty sluggish. Any help would be great.