Definitely reroute your power leads. I almost always go straight to the battery with my equipment. Depending on the vehicle, I'll install a seperate fuse/breaker block under the hood to use for wiring any gadgets I might want to have in my vehicle. Installing a GOOD quality filter in your power leads is helpful, too. You can also try to localize the exact source(s) of the noise, and filter the sources directly. Electric fuel pmps are a big issue, as are fan motors, etc,