I used to use a lot of these back when more shovels were being hopped up more often. They are a good forged piston, kind of spendy and pretty much overkill for most street motors as far as strength goes. Make sure you run at least the recomended clearance or they will score. (being forged they expand more as they heat up, so need more initial clearance. Also, take off all the sharp edges, both on the dome and skirt.
My personal experience is that 9.5:1 comp ratio is about the tipping point on a shovel for running without dual plugs. 9:1 you will probably get by without dual plugs on pump gas and no pinging. 9.5:1 without dual plugs on pump gas and you will probably have an engine prone to pinging. All of this can vary with cam duration and timing, bike weight, altitude, and even driving habits, but that is the rule of thumb I always use for shovels.