I mean that if there is no clamp in about the middle of the exhaust pipe/can assembly, then it is one piece. In this case, you can not put a different set of slip-on cans on the exhaust system unless you cut the old ones off (I would not do this though). Go ahead and put the old exhaust back on the bike if you like the look of it better and see how it runs. It is very likely that the OEM exhaust is more restrictive than the aftermarket options, and therefore you will not have as much flow through the engine. This will mean that the map you are running for the current system will be richer for a more restrictive setup. But that does not mean it won't be good since many of us feel the HD setup is too lean even with their remaps.
TQ