Hi guys, Just want to share with you regarding the M performance rear diffuser and my experience talking to the parts department person in auto Bavaria glenmarie. There r 2 types of M performance rear diffuser u can choose if u r using m-sport kit. So I'm just gonna call it diffuser A and B so bare with me. Diffuser A which is for single or double exhaust placed on the left side of the diffuser and diffuser B is for left and right split exhaust(like the 435i). I would prefer the split but u have to change the muffler. Mine is the 428i. So I called the person from the parts department in auto Bavaria and enquire about the diffuser. He told me that his not sure if diffuser B can fit a 428i because it have holes on left and right. He told me to google it and find out using the part no. he gave me. First of all he should know wether it fits or not. If he doesn't know he should find out, why am I doing his job? Funny how people work nowadays, they just couldn't care less. Anyway I did find out and it does fit any 4 series with the m-sport bumper. Now I'm not sure wether their mechanic can even install this diffuser for me. Just my 2 cents guys.