Guild Wars 2

If I had 6 pieces of armor all of which had the Superior Rune of the Pirate/Traveler/Whatever, here’s my question:

Having the 6 pieces would get me a 25% MF increase, would that be 25% for the whole set or 25% for each piece?

Actually your total magic find from a full set will be 50%, AND you could drop the last part and add another minor or major rune of the pirate to gain 5-7% more magic find OR add one superior rune of the traveler to gain 10% more. Then if you have it on a set of explorer or travelers armor thats another 18% and depending on what trinkets you have could be another 12 to 16%+ depending on level. Thats not counting any food that will add to your magic find as well.

wait how do I get 50% from a full set?

The separate instances on the rune for how many you have are cumulative, not overriding the previous ones.