ok there is the m-tech bumpers, designed for non M3 E46. It looks more subtle and curved.
there is the normal E46 M3 bumper, more aggressive.
THere is also the Rieger M3 style bumper. Similar to the E46 M3, but it is lower, and the curvatures of the lines are more subtle (the OEM M3 is more edgy sharp) The Rieger is made out of ABS plastic, isnt as nice as OEM bmw parts (i think polyurethane). If you do get the Rieger, I recommend gettin sideskirts and rear bumpers since it is much lower than the stock sideskirts and it would look kinda funny having only the front bumper on.
-If you want a bumper that resembles the M3 that is OEM, the M-tech is what you want
-If you want a close recreation of the M3 bumper without the hassle of body work, get the Rieger
-If you want the 'holy grail', the OEM M3 bumper, get the OEM E46 M3 bumper (requires bumper or fender work). This route will is what im taking