I just discovered that who ever owned my truck previously murdered my exhaust. I've got pieces of pipe ranging from 3" to 3 1/2" to 4", no cats, and I have no idea what kind of muffler. Plan on getting a MBRP exhaust cause thats what I use to run on my Stroke, but what size? 4" or 5"? I've heard you don't need a 5" until you are pushing over 500hp, but eventually I plan on it. Will I loose performance until I get all my upgrades?