is there a such thing as a 4" quiet performance exhaust system. i have a 5" WITH OUT a flow though muffler its a standard muffler and i still have the drone and its still loud. my thoughts are to step down to a 4"flow through system. I hear banks is the quietest but i am not sure and with a price tag of $575 i want to get some feedback first. If anyone knows of something cheaper thats flow through and quiet please let me know.