Just for curiousity's sake what exactly are test pipes and how exactly is it that they are better than what is used stock? thanks

 

Test pipes take the place of the main cats. They increase exhaust flow so that it creates more horsepower and less turbo lag. It's a great mod from what I hear. I haven't put them on my car yet, but it's very common to do. But you won't pass emissions testing if you have that in your area.