Extra H-pipe On Exhaust

Discussion in 'Classic Mustang Specific Tech' started by mhjo, Jun 27, 2013.

  1. I have a dual exhaust with two Dynomax VT mufflers and a H-pipe.

    I often hear rattle from the mufflers on idle, so I emailed Dynomax and they said I should have a H-pipe in order to reduce pressure on mufflers. Well, as I already have a H-pipe, should I add a second one?
  2. Well, here is the deal. First off your mufflers shouldn't rattle. If the muffler is rattling there is something foreign inside, something inside has broke and come loose or it is loose on its hanger. I can't think of any other reason the muffler itself would rattle.

    You can put a second H pipe in your exhaust but 2 h-pipes are not normal. I've only seen it done to eliminate drone or other problems caused by unequal pressure in the system. Dynomax mufflers are usually perty nasty sounding, are you sure it is the mufflers that are rattling and not something else in the exhaust system ?
  3. it's probably the flap/valve inside the muffler that's rattling. i can't imagine a second h-pipe would help.
  4. Never, in my 50 years of wrenching on rides, have I heard of a 2nd HP pipe to cure anything, let alone a rattle.
  5. I have the Dynamx VT's with movable flaps.


    The rattle is asumumed to come from the flaps when they are closed (typically at idle).

    BTW: I am very satisfied with the mufflers as they are free of drone and makes the car completely silent while cruising.

  6. I just watched the Vid. Sounds like a nice muff. I'm a little bothered by that "flap". As will it eventually stop opening due to increased blow-by?
  7. Hmmm… I have a manual trans because I prefer more direct control. If I wanted mufflers that could be loud or quiet, I'd get these, selected for loud or quiet using a switch under the dash-

  8. Poppy, a second H cross over in exhaust is very uncommon but they have been done on various performance exhausts. It is usually to eliminate drone or undesired exhaust turbulence at a certain speed/rpm.