[soundman98]

normally, that would be a fine spot to grab power. though just keep in mind, if you have a engine stall/etc on the track, that power port defaults to being off, meaning that your mxm is going to be reset. maybe this isn't going to be a problem for you, but it's just the first consideration i thought of in such a situation.

could run a new fused wire off the battery for that, if that's easier for you than tapping into existing circuits. or, if you won't be using the radio in the vehicle, you can purchase an aftermarket radio harness, and it will allow a plug-n-play connection to the power connections in the radio harness(same circuit as the cigarette lighters i believe).