You have to assemble it regardless, I dont think they ship 10' x6' pre assembled boxes.
Build your own, do heavy research on mufflers and just throw on a 36"x6" magnaflow for your reso. Custom and unique > what others have
turbos and super turbos are not loud but give a rumble, you tube works wonders
mandrel bends/true benz piping, magnaflow reso/ pair muffs and tips put me around $400 done and done