I've seen pics on CarDomain.com with c1500's and some of them have there lids flipped over. Will this hurt the truck at all, and will it help out with more air flow ?

You get better flow, but it also lets in more dirt particles. The sound under acceleration changes, but if you want to do it right, get an air filter kit from a place like Airaid or K&N.

I did this on my 74 c20 i used to have. Between that and the flex fan it sounded mean when i opened up the 4 barrels!