If you put a glass pack where the res is, it mellows the sound out more and you get a straight through flow... Sure it won't flow as well as a straightpipe but it'll be damned close.
Also, catback on our cars = waste of money unless you're getting stupid high in power.
And even moreso, how the hell do you think a V6 without a resonator sounds good? Only engines you can straight pipe are eights. Everything else just sounds like some sort of rice.