Ok well this is what i got today while testing.

XP At Level 1 Tests:

Single XP=50 Mob Level 1 XP=62 Mob Level-2
2 Guys XP=31 Mob Level 1 XP=32 Mob Level-2
3 Guys XP=19 Mob Level 1 xP=23 Mob Level-2
4 Guys XP=16 Mob Level 1 XP=19 Mob Level-2
5 Guys XP=14 Mob Level 1 XP=17 Mob Level-2

I have not tested it any further yet but for some reason i did not get Party bonus for 5 I am thinking it could be due to the fact of the level my guys are.

Other then that would love to see more tables from Duel-Boxers like this at higher levels please! Send them in!