I think the DR Low Riders you're using are round core strings. I would suggest a good hex core string like Sadowsky stainless steels. I had the same problem with an older Tobias Toby Pro. I tried everything to get the B string tighter. Then I switched to Sadowsky and BOOM, my B string was much more playable. I also raised my saddle under the B a little bit but not enough to change any intonation.
DR Lowriders are round wound on a Hex core. I too like the Sadowsky strings. Good tension and great snap.
+1 to whoever suggested trying .130 or larger.
