3" H-pipe on the '71 Charger. Only had to cut a bit off the H-pipe so the tubes are a bit closer, but this is with Hooker headers and the TTI collector adaptors.
2-1/2 X-pipe on the '69 Coronet. The X-pipe to the mufflers seemed to be too long? Maybe for those running shorter mufflers? Had to cut the ends a bit shorter.
Changing the clutch in the Coronet, getting the exhaust back off was a chore. When I put it back, I welded flanges between the mufflers and tail pipes so I can drop the entire center part of the exhaust system.
Have another 2-1/2 H-pipe system for another '69 Coronet, but it is not installed yet.