C6.R was FIA-homologated as Z06 in 2006 (prob not earlier as street C6 Z06 was not available)
Here are the most recent homologation bits for "both" Saleens
Code:
GT 013 USA Saleen Mustang SR SALEEN S7 01.04.2003 2011+
GT1 001 USA Saleen SALEEN S7 TWIN TURBO 01.05.2006 2013