The S-Coil is nothing more than a metal rod with rubber around it. The Modular is a series of individual modules all actiing with one another to send vibration out. The Modular is more effective, but the S-Coil sure has a nice price tag on it. I have 5 modules on my SB, but that is only b/c i wanted extra weight out front. But honestly you cant go wrong with either.