Buy and Apexi N1 muffler and get 2.5in piping from header/exhaust manifold back. No resonator or cat. Its the cheapest and by far going to be the loudest.

THAT WILL BE LOUD AS SIN!!!!!!!!!!

Or you can buy the Skunk2 as people are saying and take out the first resonator (after cat) and it will be loud.

You could always run a side exit exhaust with no resontor or muffler:naughty: