I am currently using stock 2 1/4 inch log manifolds. Exhaust system is 2 1/4 inch dual to a Flowmaster 70 series with single 3 inch out the back behind the right rear tire. This combination is pleasantly quiet, but drones just a bit. I plan to add an equalizer tube under the oil pan soon hoping the drone noise improves. I believe the cast iron headers from 406/427 would really be a great improvement but I think they are to expensive and I do not spin this truck much more than 3500 RPM. I am also a member of the "old Timers group". Hate change, technology, cheap beer and progress. Firmly stuck in the 60s and happy there!
William in Atlanta