viper 5900 v 7900, 791?

791xv-----Has a 1/4 mile range

5900------Has a 1 mile range

7900------Has a color OLED screen and can be re-charged.  If im not mistaken it is responder technlogy which may give you up to 1/4 mile range

All are installed the same way and have the same wiring.

No not at all, unless you like a blue remote or a carbon fiber.

The 5900 also has a horn honk output seperate from the siren output, so you don't need to get fancy with relays, diodes, etc.... Nice feature!  Status/warn chirps are also programmable on the horn if you want it to chirp like the siren.  The 791 does not have this.

I installed a new 5900 and it works the same as my last 791xv, but I need to hold the remote buttons down a slight bit longer then I did on my 791xv.  Must be something with the new antenna and 1 mile range.

I tied one of the aux outputs to my heated windshield in my Explorer, another to power up my sound system without turning the key on, it's a great unit.