Interesting, I love this old subject. You have 2 kinds of protected CDs (you have more but it's to be short and simple)
A-Music CD
B-Data CD
A- Altered TOC: You can copy everything (not bit losses) with oVERfLOW tools u others. Mixed Audio-data: The same, uninstalling rootkit stuff. etc...
In any way, that systems are not often used today.
B- There are a lot of schemes but they can not hide usefull information, only fake information, error gaps, etc... and then you must debug exe loader to stop checking it. The main idea is to jump "check original CD" routine. There are heavy systems, Starforce, and others. I know one DVD that has not been copied yet and have several years in the market, do you have got a PS2?
You must supply more information about the CD, data? audio?, what data exactly is missing?, is a setup CD? video?,etc...
Regards,