Level doesn't matter. That is why killing a level 2 dreg takes almost as long as a level 20 dreg All enemies give the same exp amount no matter what level. The only times enemies give higher exp depends on the enemy rank. For example a level 2 vandal gives 20 exp and a level 20 Vandal gives 20 exp. A level 2 Major Vandal gives 55 exp and a level 20 Major Vandal gives 55 exp. All enemies give the same exp in order for high level players to help lower level friends without worrying about wasting time not getting enough exp.