i know the factory stero in e32's is good but i had to replace my head unit so i did with an aftermarket one. wondering if anone has taken the time to add a aftermarket amp, new speakers to their car (750). Was it worth it? What brands did u use how did it sound and did u have to individually wire each speaker. also are the stock speakers a standard size? (all of them) Who makes them and or what did u replace them with?