Exhaust Question

[the07vmax]

Couple of weeks ago i heard a 5.3 Sierra on the highway with a pretty nice sound. It was a loud deep rumble similar to the one from a diesel at a constant speed(65-70). Never heard anything like that before so i asked the guy what kind of exhaust he had, but all i understood was BASS. Anyone have an idea of what he's talking about? By the way he didnt have dual pipes. It looked to me as if he was running the stock pipe with a pretty big tip (like the tips on diesels). Im looking to get an exhaust for my truck and that one sounded perfect just dont know what it was. Tried looking up BASS EXHAUST on youtube but all i could pull up were a buncha imports. Any ideas???

-Thanks

[99kon]

Bassani!