"Good" is relative in this case. Right after I bougtht my '04 4-cyl I replaced the factory muffler with a Flowmaster so that it was easier to hear when I should shift (couldn't hear much of anything witht he factory exhaust). I also liked the sound, but like I say, that's a personal thing. There's probably some posts here with sound clips, but you ought to search on Youtube. You'll probably find a clip with a very similar setup there.
2004 Frontier, King Cab, XE, 4-cyl, 5-spd, 4x1