Black smoke usually = unburnt/excess fuel.

I'm not a fan of the sound, and the looks aren't any better than stock IMHO.

It is tough to judge sound through some videos though...as they always seem decent in person. To me, that car sounds a lot like my 6 cyl Cummins.

I like this video better - http://www.youtube.com/watch?v=aJPji4zbTOw&NR=1

Poor guy thought he whooped an SRT - WRONG!