Well to properly answer this question, the best exhaust out there should have all these traits:
Lightweight, SS or Ti
Straight through design w/o creating a lot of cabin resonance. That's where the silencer would come into play.
Look, fit, and finish
Obviously power gains.
That's what I would consider to be the best exhaust.
Most of the time you get custom piping made from muffler shops it's mild steel, prone to rust and weighs more.
Rishie
I'm sure JIC will turn out to have the best system on the market.