They're bigger, there's more of them (not more from the one pickup but more being placed) and they absolutely stop me completely most of the time. A few nights ago I was racing on Chenghou and on the last lap I was in second and all I heard and saw was mines, mines, mines, mines. There's no way the first place racer pickup that many mines. There wasn't even the opportunity to pickup that many weapons let alone all of them being mines and there was quite a big margin between me and third so I can't believe they were dropped the lap earlier. I even IM'ed the guy that won to congratulate him and mentioned it about having to dodge all those mines. He didn't lay them.