IIRC it was impossible to fit Weber carbs into a Mini without modifications to the bulkhead (big hammer usually employed) or, commonly, just cutting a hole in the bulkhead so they sucked air from the passenger compartment. In the latter case nobody bothered doing anything silly such as building an airbox so they would just let the induction roar deafen the passengers. It was a favourite in clubman rally circles, and the codriver was generally employed in putting his coat over the air intakes to get it through noise regs during scrutineering.