Hello I am new to this site and joined hoping to find some info on brakes and engines. I have a 2007 mini cooper. 38k on the odometer and it needs brakes. With that being said I ordered brake rotors and pads from the local auto parts store. I removed the front rotor and the replacement ( Wearever from Advanced Auto Parts) is smaller in diameter by approx 1/4 inch. How do I determine which brake rotors i need and how do I know if I have a SOHC or DOHC engine? Many thanks..new guy... Larry