This time around you can get exalted reputation with both factions at the same time, and you essentially only need to complete a short chain of quests to get it.
The quests you need to completeBefore you are able to do the small quest chain that gives you enough rep to hit exalted with both the Gelkis Clan Centaur and Magram Clan Centaur, you will need to do a few general quests in Desolace. All the ones you need to do begin in the Karnum's Glade (the main hub in Desolace), and below is a list of quests that you need to do before you can do the centaur quest line.
- A Time to Reap
- Pulling Weeds
- Taking Part
- An Introduction Is In Order
- Cenarion Property
- Delicate Negotiations
- Will Work For Food
- My Word is My Bond
- Three Princes
- Not So Fast!
The Centaur quest lineOnce you've done all the quests above, your next step is to go just outside the entrance to Maraudon and kill mobs called "Maraudine Mauler". These will quickly drop an item called "Maraudine Prisoner Manifest" that begins a quest.
This quest is part of a four-part quest chain, and at the end of it you get exalted with both the centaur clans. There is nothing difficult about the quest chain itself, so I won't go into details about it, and you should be able to do it without any problems.
Enjoy your 2 "free" exalted reputations!