From what it looks like, there were slight modifications throughout the years. I know for a fact that different OS's were installed on the ECM's from the 07,08,09. You also had creature comfort features on the 08's as an option and standard in the 09's like Bluetooth. I also know that for 2007 the cars came with a different diff bracket than the 08 and 09's.
Other than that there wasn't to drastic of a change the years the cars were in production.
2007 Sky Redline: DDMWorks V8 Conversion- LS376 525hp 6.2L, TR6060 6-speed, Custom Magnaflow exhaust, DDMWorks Backbone brace, DDMWorks Pro Beam, BC Coilovers, Wilwood(Front)BBK, Norms Full Hardtop and Rear facia. Tuned on LS2Edit