I have a 3" exhaust (no cats at all) all the way back to a non-resonated milltek backbox and I think it sounds amazing. When you're not on it, it sounds almost exactly like stock but perhaps a TINY bit louder from the inside but as soon as you start going into boost it makes an awesome roar.
I can probably make a video if you want showing what it's like?
How much did that all cost, just watched your videos and it sounds incredible! Also what intake do you have?