First post here.

I have a 2019 BMW M550 Xdrive. This is going to be a 2 part question, because I’m a little confused.

My cousin has a BMW 2018 M540i rear wheel drive. He says car was custom made to have the M series engine and everything inside, but with the body of the 5 series. The exhaust of his car has ‘m sport’ on it while mine is blank.

The reason I’m saying this is because he said he added a downpipe to his car to make it louder and faster. My car is only 5 months old, and I didn’t add any mods to it, but I do want to make the car sound more sportier. I was thinking of changing the cat back exhaust (do you recommend?) my cousin said I just need to add a downpipe to it.