[Ice Demon]

Ok well basically the bigger the diameter the header means more exhaust flow which mean more power but there is no real difference between 1 3/4 and 1 5/8 only 1/8 difference so it doesn't really matter which one you get. I would suggest BBK longtube headers because you want to run cats and the cats come with the kit. As far as sound they all some pretty much the same I don't know of any certain longtubes that sound better than others. Also as far as a x pipe well if you like your car loud then don't get one but if u want a more mellow sound then get the x pipe. I would suggest that you see how it sound with your loud mouths first and if you love how it sounds leave it alone but if its too loud for your taste then add the res x pipe. And vids can be hard to find but there are a ton in the better exhaust thread.