Custom. Started by removing the Resonator... Still wasn't loud enough... Continued by removing the factory muffler and welding on a 3"in / 3"out glasspack. There is no restriction in the exhaust now, I will be leaving the catalytic converters in, and I will keep my Y-pipe... The only thing I need to do now is replace the factory intake. I tried running the truck with the factory air box disconnected yesterday, it solved the rest of the restriction problems...
You know when you have a really nice catback exhaust, and when you put the pedal to the floor, and then let off the gas a little bit, you get that almost gurgling sound... Yeah I don't like that, and the reason is because the intake isn't proving enough airflow... So as soon as I get my replacement intake, I'll be sitting pretty...

Also gotta get my hands on a Superchips tuner...