Hey I might be super behind on this but I thought I'd just mention that I spent around 45 minutes power levelling my 2 friends from 21 to 32 using flesh stick on my new game plus. I was level 40 we had one guy wait with Tina I went to flesh sticks spawn point killed him in two shots with my shotgun before Tina can even speak dude on the other end starts the mission again. I'm already there flesh stick instantly respawns I blow him away again whole thing takes less than 10 seconds a time and he's giving out 4k exp....repeat till your totally bored.

I REALLY hope they don't somehow patch this out. Works like a charm in the first playthrough as well, and it's really helpful for two reasons. The game isn't very fun when playing with others who aren't your level, so this allows you to even that out. The other thing is the characters don't really become as fun to use until they're somewhat deep into their skill trees.