replacing speaker jumpers improved the sound on both of my sound systems. i agree some stock jumpers are better than others, but most speakers can be further improved with better aftermarket cabling- the trick is to find the right ones for your speakers. if unable to sample a few different ones to experiment, try using the same cable as your main speaker cable.
like most forums, ask 10 different people, and you'll get 10 different answers- dont expect any solutions, just more questions to ponder... :)