Just got a '75 Eldo. Conv. w/ 500 -stock single exhaust. Can anyone offer suggestions to convert to dual? I'd like to keep it under $600 & would do one muffler (Edelbrock, Turbo, Flowmaster, etc.) w/ two 2.5'' exits, or true dual w/ two mufflers depending on cost. A friend may do the work & "could" eliminate the catalytic converter -anything to change/alter in the emissions if that is gone? Thanks in advance.