I'm new to this page so please remove of not applicable!

Picking up my F56 Cooper S, however, i wanted to upgrade the exhaust. I was told that they cant fit it due to new emission laws! What other options are available that wont effect the warrenty?

Secondly, i do a fair bit of mountain biking and use to having a roof rack but there are no Thule fittings, what rear mounted bike racks are best?

Thanks for the help!!