I'm not Frank, but will give this a shot to help you out.
The Dragula has a different header design than the S/C/S series 2-1. The S/C/S 4" is an S/C/S header with a 4" Dragula muffler, and the regular S/C/S 2-1 has a 3.5" non Dragula muffler.
I'm sure Frank will chime in to add info or correct anything if I am wrong.
Edited to add the S/C/S is an equal length header, and the Dragula is a three stepped header.
2013 RGU Ember Red Sunglo (Under Construction)
Last edited by Fire-Medic; 11-18-2012 at 06:02 PM.