Old 'Improv' 2012 Summer Tour (Mansfield Jam) riff:

E|---------------------------
B|-3----3---3-----1---1---3--
G|-0h2--0h2-0-----2---0---2--
D|-0----0---0--0--3---2---0--
A|---------------------------
E|---------------------------

New Kill the Preacher riff #1:

E|------------------*------
B|--3----3----3----(1)-3---
G|--0h2--0h2--0-----2--2---
D|-(0)--(0)--(0)-0--3--0---
A|-------------------------
E|-------------------------

* Dave does not always play the chord with the star. Instead he skips right to the next chord.

Riff #2:

E|--------------------------
B|--3----3----3-----1---1---
G|--0h2--0h2--0-----2---0---
D|-(0)--(0)--(0)-0--3---2---
A|----------------------3---
E|--------------------------

Switch back-and-forth between riff #1 and riff #2