I was recently in San Fransico and this bike went past and caught my attention with it's awesome deep grumble. It was all black, 4-stroke, loud and had an exhuast pipe on either side of the bike pointing up on an angle towards the sky. It wasn't cruiser style, but also not like a faring sports bike either. Kind of stripped back road bike like a VTR250. That's all the info I have. Sorry it's limited. Any ideas what it could be so I can further my investigations?