The factory exhaust setup was poor from a breathing standpoint. Even the dual exhaust cars had to wheeze through a single muffler behind the axle. It was designed like this to save space, as the cars are very low to begin with. I think your friend may have been thinking of that factory set up. However, I would think that straight pipes would definately be illegal, but there are many options out there. Check out some of the performance shops, there are small mufflers you can use to give you true dual exhaust, while not giving up much ground clearance. Then you can ditch the original cross flow muffler.
67 RS Convertible, 327/210hp
Granada Gold, deluxe interior (black), 4spd. all stock