Wing777
Before you plug your Sirius into a 12V wire, you better check the required voltage!!!!!!!!! It may be something other than 12V for your particular unit.
My Sirius Stiletto (which Sirius calls a Plug and Play unit) is 5.6V only, not 12V. There is a step down of the voltage in the cigarette plug. I would suggest that you check your manual, the area around the power connector port on the radio, and/or the output voltage indication on the AC adaptor if you have one. Much better safe than fried.
If you want to hard wire your setup to the bike or your car you can get a variable voltage unit from Best Buy that they use in their vehicle installations. I'm sure Circuit City and other places that sell and install Sirius equipment would be able to help too.
Jeff in sunny, 75F Naples, FL