My Jimmy sounds pretty good right now, it had dual glass packs (blue streaks i think) and it also has the stock, rusted exhaust manifolds. I want to put headers on it, will headers alone make it sound louder.better? I'm also thinking of replacing the glass packs with the flowmaster 40 series 2 chamber. Would those make it sound better? Also how much hp should i get from headers, will i beable to feel the difference?