I have an '88 420SEL, and I'm in the middle of the "remove everything" process. So far, I replaced the Becker with a Kenwood eXcelon, and replaced the stock front speakers with an Infinity Kappa Component set. Just this set me back $900, plus several hours of work. It's worth it though. The quality of the Kenwood/Infinity setup is outstanding. It's painstaking, and costly to upgrade a 126, expecially if you have the 10 speaker system (who the hell thought up 4 tweeters in the rear deck???).