I was wondering what そいつら means, and is 知らんからな slang? Here is the sentence:
俺はそいつらのことよく知らんからな。
I know they slur their vowels to make things easier to say. Or maybe this is a new word that I can't find in the dictionary.
そいつら means "they"(or more precisely "the fellows"). When "ら" is added to a pronoun, it becomes a plural one. For example, 彼 means he, and 彼ら means they.
知らん means 知らない, which is kinda oral expression. The whole sentence means "because I don't know much about them".