Snoopy answered most of your questions.

You may want to look into the Apexi Worldsport Cat-Back Exhaust System's as well. They are a nice quiet exhaust (nearly stock) and still have very very nice flow. IMO the nicest exhaust out there for an Integra with minimal or even medium mods.

Also, personal choice, I prefer the Comptech 4-2-1 header over a DC Sports, and a GReddy Stainless over a DC Sports as well. Just for mere looks, quality, and lack of cracking with the other two.