Am pondering switching out existing 3.5Liter engine for a M Power 3.5Liter from an M5 in my CS. Has anyone done it? Have been told it would fit without modifying too much. Obviously, brakes, suspension, and transmission come to mind. I would think the car would just holler. Haven’t really pressed the car above 100mph fearing how secure it is. Rather, no issues pressing the Tii above 100. It feels more solid than the coupe. CK told me not to expect a road racer from the CS, but more of a high speed boulevard cruiser. Not sure what to make of it? Can vaguely remember the coupes while at college being so graceful but not too much performance. I needed more room so opted for The Bavaria/3.0S, sn#3160037. That car could do 125mph all day long and keep mpg’s in the high teens. Of course, it had to have a manual transmission!