Aftermarket carstarter on e90 330I

Hey guys I have a 2006 BMW 330I and winter is coming. I want to purchase a after market car starter but have not heard any good things about it from the dealers, but I know on any car the dealer will always say that. I have a friend that does this for a reputable place in town. He was looking into it for me and he has never done a BMW before and he said he could not find any tech support after 2005 for the 330I. Does anybody know if this is because its a definate no no to install an aftermarket car starter? The dealer said that its a no because BMW are so hightech with their wiring/electronics that installing a starter has been know to mess that up like setting off the Airbags. What do u guys think? I live in Alberta Canada where it can get to minus 40 and a carstarter would be great

I was wondering this same thing about a year ago but I was concerned about voiding my warranty. If you do decide to go for it, make sure to report back with the outcome.