I have a 2003 mustang gt 5 speed. I just put on a bassani o/r x on and I already have 40 series flows on. Well its loud very loud WOT it sounds awsome but it sounds like something rattling when i let off the gas.I checked everyhing under and tighted all the bolts with a impact and i checked for leaks and nothing. Is this suppose to happen cause its new and will go away or what. thanks for all the input