Running a H Pipe,whats the advantage

Thanks you everyone for you much needed feed back and advice, i see that its the x pipe and not the h pipe is the way to go. I already am running hedders with dynomax mufflers, can the muffler shop weld in a x pipe like they can the h pipe, locomation has his behind his hedders he has a dart sport like mine . I dont want to put on a whole new exhaust system, can the x pipe be welded on my exhaust system the way it is? advice is allways grateful NEWATHIS