Never plead guilty in California. You have 3 opportunities to beat a ticket: trial by written declaration, court trial, and appeal process. The latter two require the officer to appear in court (in contesting 4 speeding tickets, 3 times the officer did not show up and I won by default, the last time I had the law on my side).
Knowing which CVC you violated will help determine exactly what the law said you broke. Highway speed laws are different from surface street regulations.
check out
Help! I Got a Ticket! It specializes in helping California drivers fight speeding tickets. It's all reading material, no books or bs to buy and it's step by step how to beat a speeding ticket. Good luck.