JckHmr

Test Pipes would be the cheapest way to make it louder if you're on a budget. Just make sure you have to tools needed to remove the OEM Cats and secondary transportation if you bust a socket/wrench.

Another option is Short Tails (Muffler Delete). I had AAM Short Tails for a few months before saving to buy a full CBE and absolutely LOVED the sound. They cost a bit more than test pipes new, but you can get used ones for relatively cheap (I'm actually going to be selling mine here within a few weeks). I even debated fabricating my own X and Midpipe to kill the drone and resonance inside the cab. After tearing down the OEM exhaust and figuring what I would have needed to do without a Mandrel Bender, I decided to buy a complete CBE.