Hi everyone i am looking to buy a remote start alarm for my 96 318 i have found 1 but do i need to buypass the factory fitted imobiliser cause the alarm comes with an imobiliser?????

used: i am confused as the guy who is sellin the alrm says i dont need to but everyone else says i have to ????. can anyone advise me if i need to and if i o how do i do it ???
cheers for any feedback