You will need a Breaker bar, no swivel. there will be enough play in the extensions to get it on the nuts, I think I actually broke 2 of them loose with the Bar above the exhaust pipe.
I did use an air ratchet to take the stock manifolds off, and if you might check, they are 1/2 inch, but I did use a 13 mm wrench putting them back on, makes it easier to get the box end on through the headers.
2013 Performance Package V6
2013 F150 6.2L Boss
Yes it is a Boss