The Duke has the same stator as all other 690s - Enduro (R), SMC, Supermoto, Rally Replica. Unfortunately there is no higher power version available that will fit, neither OEM nor aftermarket.
Work on reducing inefficiencies, like going to better all LED and/or HID lighting (obviously blinkers with a proper relay), replacing the stock regulator with a MOSFET one (Uller and RoninMoto have done a write up), using dual element heated grips instead of resistors, etc.
Proud member of the HUSABERG ADVENTURE TEAM!
12 690 Enduro-R, 12 Husaberg FE570, 09 KTM XC-F/ 450 RFS hybrid, 07 KTM 450 SMR, 09 BMW F650GS twin/F800GS hybrid, 03+05 YZF-R6