I bought some meguires plastx and it works great for my headlight lenses. But the only thing I can't get off is some crusty looking snowflake stuff on it. It's clearish but makes it so I can't see through them still. How would I go about getting this stuff off? Maybe some very fine sand paper? If so What grit?

i think what you are talking about is almost like a clearcoat layer that is peeling off.... here is a writeup (http://www.3.8mustang.com/forum/showthread.php?t=114484&highlight=headlight+restor ation) on how to make them look new again. you should check that out. tells you step by step how to do it and exactly what to use.