FreeBSD Security Question.....

Ok, I had a question for you FreeBSD addicts,
After you change the secure level to be 2 or 3 and you set certain files and directorys immutable is there anyway to get around that?
The only way i have found so far is to boot the box into single mode......Im a pretty smart guy but i don't know everything.....so I thought i would see if any of you guys knew.
Oh and ive set up in my /etc/rc.conf file the kern secure levels are on and equal to 2. And this file is set immutable.