Alarm systems

[Hot Rod]

I just got an 05 SE with the v8. i now need an alarm system. I was told i can get a better deal aftermarket rather than at the dealer. Any recommendations on brands. I would like something that does not have that annoying chirp when i turn it off and on. I would like the lights/horn etc. to sound. Does this affect my warranty at all by getting an aftermarket alarm installed?