I've been doing a lot of reading and have learned that a cat-back system "opens up" the exhaust so the engine doesn't have to work as hard to get the gasses out.

My question is this: On my 05 civic ex, aside from the giant muffler (which I understand clogs up the system), the actual exaust piping from the cat to the muffler is completely straight already. Do I need a whole bolt-on system or would I get the same resuts just by replacing the actual muffler?

Sorry if it's a stupid question - don't know if the piping is a different diameter or something on the cat-backs.

Also, does anyone know if the Tsudo Fireball extreme is any good? I'm having trouble finding kits that fit my year, although I've heard that anything for a 2002-2003 should fit fine.