Sandy,
My mind was wandering again this morning, and for some reason this thread popped into my (vacant) mind. I think I know now what your dealer folks were talking about. I seems that H-D is moving into the 20th century and is installing a closed-loop injection system. That means there will be an oxygen sensor in the exhaust system that will feed back info to the ECM, which will then be able to make minor corrections to the mixture (major differences from the programmed values will just set a code, similar to the way the system works in your car) . This still doesn't mean you can't change exhaust systems, however. Drilling a hole and welding in a threaded fitting for the O2 sensor isn't very difficult, and you can bet the aftermarket folks will have the fitting in their pipes anyway.