This is the real Shure instrument mic.  I don't understand how 58s are regarded so highly, because I have never used a 58 without it sounding very muddy.  If you completely cut the bass on a 58 then it can sound cool.. but still not accurate.  The 57 grabs the sound you hear.  It is still a bit bass heavy, but not overwhelmingly so, and definitely not in a way you can't fix by tweaking your EQ.