I doubt Chicago requires evap canisters, but find out to be sure. if they don't, tell them not to install it. If they do, i would because if it's mandatory you may as well be legal since it has absolutely zero affect on the bike in any way shape or form. All it does is capture any fumes that come out of the tank venting and send it into carbs on a carb bike, on the Tbird not sure if it directly sends them into the injectors or what. But thats all it does is keep fumes from escaping into the atmosphere.