Ok, there may be exhausts that sound quiet, but during cruising speeds and idle, would they produce a humming noise? I dont mind at all if they're loud (like mustang loud) but as long as they dont have that humming noise cruising at 65 mph, then I'll be happy with it. Now, with that said, in a turbo boxer engine, which exhaust will not produce that annoying hum during cruising speeds. i hope im making sense becuase when I took long trips in my altima with a 2 1/2 inch exuahst with a free flow muffler, it had a nice deep tone to it but it also had this really annoying barf-inducing hum to it that drove me absolutely crazy. Im considering the greddy catback, would I be ok? please help.