im running flo pro 5 inch on my 6.4. it hangs lower because b&w gave me a drop bracket so it would clear my gooseneck hitch. its about 2.5 inches lower than normal
You should be able to remove that drop bracket. I have done a few exhaust 4" and 5" w/ b&w hitches installed (Including mine with 5" and B&W turnover) and found the drop bracket only necessary for abnormally large bend of the stock exhaust over the axle