You've probably read over 200 exhaust stories and, right now, are wondering why we're doing another one. It's simple. An exhaust is usually the first or second aftermarket performance part anyone slaps onto their car. More importantly, a bolt-on exhaust system is a rather quick and simple install. And even more important than that, it makes power. Well, most of them do. We'll slap a Magnaflow after-cat system onto an '06 Honda Civic Si and see just how much power we can gain from a couple shiny pipes.