These are in the AMT '69 Cougar XR-7, kit #2202.
The white mufflers could be used for glass packs. They are supposed to represent the stock mufflers in the same Cougar kit.
The yellow ones are supposed to be stock mufflers in the AMT Snakebite '68 Mustang kit.
These orange ones are in the above Cuda kit. The 'Killer 'Cuda' kit doesn't have them. It is set up to only have side pipes, if it is built out of the box.