Depends on mods, number of owners, and running condition.
For example, I am selling my '00 RS with several mods (suspension and engine) for $11,950. I am the original owner, and it runs great. Mobil One every 3,000 miles, etc.
Each car is worth something different, so it would vary. A good bet would be to check Kbb.com and NadaGuides.com and then average the two values. Then, offer 10% less.