While the EASIEST place to kill Xenos is Colorado, it's one of the worst. The pilots there are all Rookies (that I saw). Killing a rookie has the least effect on your rep. The guys near Nome Base (the Xeno base in the Kepler System) fly Hawks (I think) and are all Aces. Between the combo of flying more powerful boats and being Ace pilots, you get a LOT more net effect per kill.


Also..if you're trying to raise your rep by killing Xenos in Kepler, do NOT TAKE MISSIONS TO DO IT. The missions are all given by the Bounty Hunters, NOT the Zoners. Because of this, any positive effect on criminals killing Xenos might have is totally overridden by the fact that you were working for the Hunters.

The better way is to just hang out near Nome. Kill the two weapons platforms every time they come online, and wait for ships to pass. Every 2-3 minutes, two Aces launch out of Nome. You need to kill these fast, since they generally run away immediately (at least, they run from me - I fly a maxed Eagle). Also every couple minutes (though on a different schedule than the launching fighters) a wing of 4-6 Xenos will fly within 2 or 3 klicks of the base. If you see these guys on your scanners, immediately get as close to them as possible to attract their attention. Even if you're already fighting the two guys that launch from the base - once you get them to start fighting you, they won't leave.

Hanging around Nome, I usually get around 20-30 kills every 7-10 minutes. Since they're Ace pilots, this amounts to about 1 box per hour on the majority of criminal factions, and 1-3 boxes on the corporations and other people. Certain Criminals also raise faster than others, most notable Outcasts - they really like Xeno killing.