There is a guy who fit the v8 out of the E46 M5 into one, the ironic thing is that was still slower than an E30 with the s14 (inline 4) still in it around the Nuremberg Ring. Don't get me wrong I know this car and engine are not perfect but as an over all package they are a pretty good combination. I just don't understand why people would choose a M3 to swap, but in the end its just a car and the owner should do what makes them happy...