NellyA1

Hey guys, I just got a 2011 A1 and looking to do some modding to it. My first mod is wanting to change it to quad exhaust like the S1. I know I have to change the diffuser as well, but my question is do I have to change the bumper too? Or can I keep the original A1 bumper, and just change the exhaust + diffuser. Or are there any other requirements or specification to do this conversion that I need to know? Thanks a lot!