Not trying to hyjack the thread, but... I was looking at this exhaust for my car too. There seems to be varying information on whether the original HIPO cars had a muffler. Or did they just use the resonator? Thanks.
I've seen originals with mufflers, and I've seen them with the chambered intermediate pipe. They all had the resonators. The ones with mufflers were automatics though. The one I absolutely fell in love with was a '66 Formula S with a 4 speed and the chambered pipe. 44 years later and I can still get wood over the sound of that thing going by the house around 6000 RPM in 3rd gear. Best sounding exhaust ever put on an A body.