[SOLVED] How to make my character (properly) look where the camera/mouse is pointing?

Update: It's fixed! I found a new script for proper head movements, and added tweening and waist movement to it, along with other improvements. If you still wish to see the old question, here it is. I've removed the script, though.

I've been working on upgrading Dominical's script for making your R15 character look at your mouse, and so far it's been working out pretty well, I've added options like variables for how far your head and torso can rotate, whether your character looks with the camera or the mouse, and an option to make the whole character rotate towards the mouse, and I've used CFrame lerping to make the rotation smooth. But there's one last thing I've been trying to add and haven't been successful in yet. I've been trying to make it so your torso looks left and right towards the camera/mouse, like in jailbreak, meepcity, and robloxian highschool. It works, but it only works properly when you're facing one direction, and every other direction messes up the rotation. I have a feeling there's just a few things I need to add or change, but I'm not sure if that's true, and if it is, I don't know what to do to fix this. Can anybody help me out here? Here's the script:

--Removed the script. I don't care if it's broken, I don't want anybody stealing it.