I purchased a magnaflo Muffler and Mandrel bent up stainless pipes for it.. Its very suttle till its romped on.. then it has a lot of volume. Gains were noticable.
Mine is Stainless ( muffler still looks chrome plated after 2 winters in NY, high quality stuff ) .
ShyBri has a Gibson dual setup. Its much quieter then mine ( his is less then 3 months old tho and hasnt ' cured ' ) . His is that aluminum stuff and we both think its going to get hurt in the salt/snow this winter.
Most will tell you to get a flowmaster.. if all you want is sound, thats the way to go, cheap and very common. I'm biased, I had a flowmaster and didn't like it at all.
Rumor has it Borla is the BEST overall, but it comes with a premium pricetag. Well worth the money.
Anything beats the factory setup, we will all agree on that