TimeShift

Here's a list of the maps you need to beat to unlock this achievement;
• Big Bang Boogie
• Can I Kick It?
• Don't Push Me
• King Of The Ave
• Life Lived Slow

As stated in the description you need to be playing ranked games for any wins to count toward the achievement, however you are able to play 2 player ranked matches which makes boosting very easy.

All the maps are quite small and you shouldn't get lost looking round them, just try and meet up in the middle, to help speed up the process have the host player create the match with a 1 kill limit, each game should take around 30-40 seconds!

This is quite an easy achievement to earn. The DLC for TimeShift is cheap, so download both DLC 1 and DLC 2, and then with a boosting buddy, set up ranked matches on each of the new maps, taking turns winning them.

See this article for more information:
http://www.360-hq.com/article-2630-thread-1-0.html