Richardmr, I think that you're right about many different things being able to make a sonic difference in the system. It's hard to know what will be best. However, in many cases, what is best for me might not be best for you, due to certain synergy considerations.
Therefore, I mentioned the recommendation of "don't season your food before you taste it". I think it makes sense to see what you've got before you change it. Not all changes are upgrades.
FWIW, I think that Discovery tonearm cables are used by many high end tonearm makers, and they are quite good. But they may not be better than what came in your arm. At the level of a Tri-planar, you are getting one of the best arms in the business. It's a good bet that there are some very nice wires in there, in stock form.