If you add emergency lights or sirens they should be professionally installed by a local Federal ?Signal or Whelan dealer. The worst thing is to be responding to an incident and suddenly having your lights go dead....also make certain your siren pitch is not similar to any other units to avoid the intersection issue of the sirens canceling each other out due to common pitch. The other thing to watch out for is the insurance issue; in many states you are not covered unless you have a rider for the equipment and it's use.
In NY state light bars are magnets for State Troopers who consider the IPO devices and can issue tickets under the "bright lights law". I think other states have adopted similar laws.
One other thing is make sure you have rear lights/LEDs...to avoid some phone talking nitwit running into your stopped vehicle. The most noticeable warning lights, according to the NTSF, are the headlight "wags" or headlight housing mounted LEDs. Check the CA life guard service for how they rig their Jeeps.