Agreed with Joe, "deep" tones tend to come from systems with a resonator and a chambered muffler. This also results in a somewhat quiet exhaust.

"Loud" exhausts may have a resonator, but almost always have a straight-through muffler (think Apex'i N1.) The only way to get a "deep" tone from a straight-through system is to have an engine that displaces three litres or better.