Jumper Cables - use the stock or should they be upgraded ?

........a quick question to the Audiogon group ; should the '' stock supplied '' jumper cables be upgraded if you do not plan to bi-wire ? Also, will it really make a sonic improvement ? Thank you in advance.     
What speakers do you have?  Does the manufacturer suggest biwiring?
Upgrade the jumpers it's a relatively cheap upgrade that's a significant sonic improvement if you don't intend to bi-wire.
Wilson Benesch Square 5's and bi-wiring is not required...now back to the question friends
For a pair of speakers of that quality, biwire all day long, twice on Sundays!!  Pick up a couple pair of quality solid core speaker cables and get out of the speakers all they can give. The owner's manual for the Square 5 Does discuss the virtues of biwiring.
I was just researching this on the web last night. I found the argument made by
electrical engineers and some speaker designer the most convincing; they basically claim that the contact point at the provided jumper measures an extremely low resistance compared to the xft of cable and mostly speaker, and the 3in long body of the jumper measures even less. They conclude by saying that trying to improve a speaker performance by changing jumpers is a little bit like trying to improve the aerodynamics of a turtle. I prefer the manufacturer’s jumpers as they look neater than my 3in/10awg ofc copper conductors.
Yes, absolutely replace the manufacturers jumpers, especially if they are those uninsulated bars.

I can also recommend trying to connect the positive lead from your speaker cable to the positive lead on the tweeter terminal and the negative speaker lead to the negative woofer terminal. It may make an improvement and is free to try.

I would never have believed it, but changing the jumpers may change the sound. When I had my Harbeth SHL5's, changing to Audience AU24 jumpers cleaned up the somewhat boomy bottom end I was experiencing and made the bass pitches much more defined.  But different isn't always better, so I would suggest trying some aftermarket jumpers and seeing if they improve the sound to your liking.  BTW, when I had my Opera Callas speakers, the aftermarket jumpers rendered no improvement whatsoever.  So that pretty much sums it up, IMO. 
Of course! Even molecules soon can be upgraded ye kiddin' me?
The Vandersteen website has some great info under the faq portion regarding biwiring. So does Audioquest. I recommend biwiring your speakers if the manufacturer has gone to the detail to develope a high quality crossover.

As for manufacturers jumpers, I recommend replacement. Using the same cable manufacturer and exact cable construction as your speaker wire. Additionally, Nordost’s website has examples of different jumper configurations.
Google - nordost jumper cables pdf -To split or not to split -

I agree with viridian.
Also, you can easily make your own jumpers out of the many bulk speaker cable or hook-up wires available.  Put a spade connector on one end and a banana on the other so you can attach them without interference from your speaker cables, regardless of whether your speaker cables use spades or bananas.
Finally, if you plan to keep the speakers for a long while, consider removing the binding post plate and soldering the cables to a single pair of binding posts for the best connection, then no jumpers are required.  
I have found that good quality jumpers sound much better than the stock jumper

I would use one run of the best speaker cable I could afford, and a jumpers made by the same manufacturer, rather than bi-wire cable of a lesser quality and no jumpers
I have used the Nordost  Reference Bi-Wire Jumpers and they were a major upgrade over stock jumpers... without doubt. The quality of the speakers you own... and your ears... will benifit highly.

With that said... I now bi-wire my system with identical speaker runs. My opinion is if your speakers have high resolving power...go with bi-wiring. Its a much more expensive proposition ... but the sound quality improves dramatically.  my 2 cents.
.....the current speakers cables are the Cardas Clear Beyond and a 2.5 meter pair were almost 5 figures......ouch. They took me awhile to pay off. I will check with Cardas as getting another run of those speaker cables in order to bi- wire is out of the price range. I will check with them to see what jumpers they have or would you run / use another company's ????   
I would use jumpers made of Cardas Clear Beyond if available
Whilst we're on the subject, jumpers aside, different results may sometimes be obtained from connecting the single wires to the upper or lower set of binding posts.  Some do one upper and one lower.  It's worth a try.  
I just bought a Nordost Norse jumpers I have not try them, I used heimdall 2 on top n clear day on the bottom, for my diapason, they sound amazing, I moved the diapason farther, so the clear day are only 8 ft, I felt the Norse might equal or maybe better, I have to try first to know if indeed are better than clear day, I saw vertical Biwire go on Nordost web site, this might work, will see.