There are 9 New Kolb Aircraft MARK III XTRA aircraft on the U.S. registry that TailWiki has a page for. Every one is built from the public FAA record — year, serial, engine, home base, and registration history — and owners and pilots add photos, trips, and stories on top. The ones listed here were built between 2008 and 2013.
N816JK
2013 Wheeker Larry C KOLB-MARK III XTRA
Coos Bay, OR
N337ST
2010 Wilkes Jack E KOLB MARK 3 XTRA
Orlando, FL
N375TS
2009 Krips Jack E Jr KOLB MK III XTRA
Winter Park, FL
N381CS
2009 Spoke Craig A MARK 3 XTRA
Richmond, KY
N415SB
2008 Abbott John R KOLB MARK III XTRA
Fisher, MN
N1769H
Parker Cory J MK3 XTRA
Hamilton, OH
N284MX
Hamby Scott KOLB TWNSTR MARK III
Custer, SD
N359RB
Branson Charles KOLB MK III EXTRA
Stayton, OR
N478J
Rainville Lawrence KOLB-MARK III X-TRA
Page, AZ