So, after watching many youtube videos, I am torn with what to do to my exhaust.... LMC offers catback with resonator tips (muffler delete) Straight piping Glasspack If I straight pipe it, will I kill my gas mileage? I heard someone saying that it messes with the 02 sensors... LMC's catback looks amazing, and will probably sound it too. But I would want to punch out the cats as well. Would that harm it any less than taking em clean off? Glasspacks, well, I would just take the flowmaster off and get new tailpipes for it, most likely a y pipe, or get two glasspacks and run em without cats... The ultimate question is; will messing with the cats ruin my truck? Or just cause a slight decrease in gas mileage?