Well, technically, it's not illegal to modify emission control systems on your vehicles. You own your vehicle and can do what you darn well wish to do with it. You can bury it in a hole, as long as it's not against the law. The illegal part is operating your vehicle on state or federally funded road ways without the federal emission system in operation, or modified. For off-road use they can't say anything about it, and I've been down that road, unfortunately, many times, as I use my trucks a great deal off the road on the ranch. Originally, we had to remove the cats on our gas trucks to keep from setting the pastures on fire, then we went to diesels to enjoy not having to do anything, including down shifting. Now we are starting all over. I've gotten away with it a great deal due to leniency from local authorities, who always understood what it meant to be a farmer or rancher. Now we have the overeducated amongst us, who, in their great education, can't even feed themselves if their lives depended on it, literally. Sure they can calculate how much torque and rpm would be needed to drive a dually truck 60 mph down the highway, but can they grind their own flour for bread? Can they cut a steak from a carcass to eat, even when starving? Do they even have a clue what is involved with making bread, from preparing the soil to planting, growing, harvest, transport, processing, and finally baking it for the product to feed the masses? I believe the few that do are a rarity and certainly not in charge of building our beloved work horse trucks, light duty or medium. God bless those amongst us who can only do what they read in a book. As far as DTR is concerned, let them hang themselves. Politely, I will step aside and let them jump off the edge. When they are gone, we shall continue our conversation in peace. Another right taken for granted here in America, the right to not claim your right to the Fifth Amendment!?!