Hi,I've seen alot of threads on here stating that the wheel arch's must be changed when swapping to the OEM aluminum running boards. I just called a reputable BMW dealer in my area and the guy in parts told me that he's been selling them since they came out, that he checked his books and computer, and asked two guys that have installed many at the dealer and he stated you do not need to change the wheel arch's. He said all you need to do is swap out the running boards themselves. Can any body confirm this? I'm confused as to why people on here say you would need to replace them? I clarified with the guy at BMW that he was talking about a 4.8is and he said "yea I know, you have wider arches and 20" wheels". I'd like to purchase the $700.00 kit from BMW but want to make sure thats all i need as he said.