So I've my 2006 V6 4.0L mustang for a little over 2 years and I bought the Ford Racing True Dual Exhaust Conversion Kit for American Muscle like a month after I got the car. I started the get a rattle about half a year after and thought it was my catalytic converter. So I replaced my cats with SLP High Flow Cats from American Muscle. And then the rattle just got now. I work at a Ford dealership, and just yesterday I was fed up with this rattle so I pulled my car in the shop and removed my exhaust back to the x-pipe to see if I could figure it out and fix it. The company who installed my exhaust and cats, I had them check it out before and they said it was the driver muffle and if you hit the bottom you could hear like a little piece of metal bounce inside. This was my goal yesterday, was to try and get that piece of whatever out. But I couldnt even get it to move, so with the exhaust off I decided to see what it would sound like just having headers, high flow cats, and an x-pipe on, cause I still had the rest of the exhaust off. And a buddy I work with has a 99 GT mustang and he said he runs his with exhaust only back to the x-pipe and no problem. I started reading about back pressures and stuff and not sure if I would be able to run my car with exhaust ending at the exit of the x-pipe???? I drove it around and yes it is loud but it doesn't sound too bad and now I don't rattle like a freakin honda. So I'm just wondering if anyone has tried this with the 4.0L v6???