KutenFLHX... No, that is not the correct part number for the new 4" Rinehart Mufflers. Those are the old 3.5" mufflers. As far as I know, Rinehart doesnt even have the new 4" mufflers (slip-ons) on their web site yet. I did it the easy way and called Fuel Moto direct. Told them what I wanted... They new exactly what I needed. They even mapped the Power Commander 5 for me before they shipped it out. So, I recommend calling Fuel Moto, or Dr. V-Twin or any of the other forum sponsors and let them know what you want. They will know exactly what part number it is for your 2010 Street Glide.
Those new 4 inchers are bad-ass! And yes, the V&H Power Duals header i put on my bike is a 2-1-2 set-up.