Any other lowering is going to severely impact handling and cornering clearance. I'd tread VERY VERY cautiously.
I knew someone many years ago that bought a BMW K75, and when she found the low seat wasn't enough, she put on lower-profile tires than were recommended by BMW, had a lower shock custom made, and had the fork tubes raised in the triple tree. She could now flat foot the bike, but had to have the side stand cut because when it was lowered, the bike leaned the wrong way and fell over. Plus, it took THREE big guys to heft the damned thing up onto the centerstand.
After spending literally thousands of dollars on her modifications, she ACTUALLY said: "This thing handles LOUSY, I don't know why everyone says BMWs handle so well..."