I need to tap into switched fused power in the engine compartment (pass side firewall) for the water/ meth controller and inside the cabin both switched power and full time power. I know I could use the radio power (has both switched and unswitched) but it's already running the radio and a couple gauges and I don't want to overload that wire/ fuse.

Where should I tap into power? I could run the wire from the engine compartment into the cabin pretty easily.

 

any red/white wire in the bay. But I'd just add a fuse into the fuse block.