Selling a brand new (never used/installed) set of ARH Headers followed by a 3" X-pipe system that extends back to the factory axleback mufflers. I purchased these a while back but never got around to installing them due to my neighbors already complaining about the stock exhaust. Again, these...

is there much of a difference between the two besides diameter and price? Or or there any fitment issues for the bigger diameters? and do they both bolt on to the stock mufflers ? was looking to keep my oem mufflers but run arh catted long tubes with their x pipe .