The DNA setup allows more air into the motor, you need to compensate with some more fuel or you'll run too lean (and that's bad).
KevMod will put more fuel in in a low cost simple way, a PC-v will adjust the fueling over a wider range, much higher cost.
The KevMod O2 Tuner makes a difference at lower revs too. But not essential to running the DNA filters
Take a look here ->
http://www.xt660.com/showthread.php?t=26877