best way to make exhaust louder?

[blue00gt]

You'd lose a ton of low end if you went 3.5", plus the most of the biggest aftermarket catbacks are 3" (which is still too big unless you have forced induction). The easiest way to make it loud is to run an offroad H- or X-pipe. But if you need to run cats a crossover pipe with just 2 high flows will definitely help. My friend runs longtubes with a catted H and MAC mufflers and his is really loud for a catted car.