What kit do you have currently? You can use two sticks from your current kit, if you wish. The Impact is an utter beast with memory. Choose one of the GSKILL TridentZ in the 3600Mhz bin if wanting a new kit.
If not, you shouldn't have much trouble at all using two sticks from your current kit, possibly accounting for guard-band and using 20mV on top of XMP.