So simple my pet chimp did it for me.
The absolute hardest part is behind the air filter there's a fiberglass piece that sits in front of the firewall. Getting it out isn't very difficult, getting it back in requires some patience. Mine fit really tight and it was one of those things that it wouldn't go in no matter what. Magically it just popped right in when I tried it for the tenth time.
Also have good lighting, connecting the siren wires requires a little reaching back into a cavity that's a bit of a stretch and hard to see if it's dark.
Don't want to dissuade you, just some helpful tips. It really was *extremely* simple and there's no way that anybody could possibly take two hours to complete it.
Be aware, to activate it you still have to take it to the dealer and they'll charge you 30min ($50) to do it. If they want to charge more go to another one.