...Go with the 'Matsumoto' Headers from 'Hall Pantera' and at the P.I.Motorsports Store. The Collectors are Huge at 3" (?). On The GTS Headers, the Collectors are Very Small… almost the same size as the Primaries, themselves! Is that Restrictive to 'Volumetric Efficiency'?? YES! You can get the Headers 'Thermal-Coated', or Plain, as I did, and paint them with 'Flat Black' Header Paint. The Deeper Roar is in the Larger Collector. Then use 2.5" Pipe to the Mufflers. I used 2.25" Pipes, as the Larger Pipe offers Less Clearance from the Short-Shafts. These Headers are offered for 351 Cleveland And the 351 Windsor. OR Bolt Cleveland Heads on Your Windsor Block, building a 'Clevor' and use the Cleveland 'Closed-Chamber' Heads, and Build More Power.
NOTE: The Exhaust Pipe is Routed UNDER the Short-Shaft, and OVER the Lower A-Arm And the Sway-Bar. The Larger 2.5" Pipe WILL Rub on the Shaft when driving over Bumps and Undulations, the Reason I stayed with a 2.25" Pipe!
The Mufflers in the Photo are the Stainless Steel Units, that use to be Sold at P.I.Motorsports, but I have not seen them listed recently. They are 2.25" Intake. The Original 'ansi' Chrome 'Tips' were taken off and re-welded back-on to these Mufflers.
Good Luck with it.