big diff between open headers and full length exhaust.
You heard how mine sounded, not much more lumpier than the .528 in my 340, definitely a diff but you know what I mean, thats what more swept volume/cid does.
Muffler choice will impact tone as well, what mufflers does he have?
You might like the sound off the cut outs but probably won't dig the performance until you go up in gear and richen it up even more either.jmo
are you driving it yet?