Well, Sway bars REMOVE grip in cornering. I would start by taking both them off, setting up the car so its neutral without them, then you can add them back on as you see fit.

From what I remember the sways on the HPI's are sorta ineffective as a sway bar anyway, they are pretty much just another spring for the arm.

Also explain the issue more, is it over steering into a corner? pushing out of a corner? Also a great deal has to do with brake/throttle attitude entering a corner, how you apex the corner, ballance shifting on entering the corner. etc...