Engine configuration dictates ex. sound more than anything, Inline sixes drone @ high rpm, I wish my truck sounded more like an 855 @ highway speeds, which is a six also, just spinning a lot slower, My Detroit powered Dodge @ full tilt has a wail that can be heard for blocks but it's still a drone, alot of comp. will give you more "crack" in your ex. tone but it turns into a drone @ high rpm. I think ctd's have a great mechanical presence. Here is a test you can do, take a large metal can, fill it 1/4 way with screws,bolts, nuts,and silverware,shake it vigorously,sounds like psd, How'd ya like to work w/that?!