not 100% sure, but shouldn't be too bad
I drove my 3vz for 5 months with a straight pipe; flex pipe rotted away
it sounded pretty beastly, got a lot of compliments on the sound, but it was hella loud.
without a cat, but with everything else attached (res + muff)...
you're looking at a more hollow sound, like a Murano or 350Z kind of sound.
as far as resonator effects, well, now I've got a waaay smaller resonator than OEM, sound is... well, not quite sure how to put it... louder than oem by a bit, and it's got a nice growl to it. I think a larger resonator would kill such a growl.
suggest that you check an exhaust FAQ though