The best way to go is what your wallet will let you do!
There are various makers of catback systems out there. The range is big. I personally went with a $350 Flowmaster catback system. The other systems like Corsa and Borla are stainless steel systems. Last I checked, the Borla's for $510 for a pair of mufflers and $200 for the rear y-pipe with mufflers and y-pipe being stainless.
There are muffler eliminators that cost less than either Flowmaster, Corsa or Borla.
It all depends on how much money you want to spend. They all produce about the same gain in power. It all comes down to money and the sound that you want.