i think that the no low end thing is from a lack of backpressure because the kazuma is just a big pipe with TRD
on the tip. i havent heard it in person, but it is definitely loud. and i do mean LOUD. it so loud that i dont know of anywhere where it is actually street legal.
there are a lot of threads about the kazuma and there have been a couple of movies posted of what it sounds like. you should try a search here and at nc.org too. i think that everyone that has gotten it has had it modified in some way, just to make it bearable. i think that most people have a resonator welded on after the cat to try and make it quieter. if you want to add a muffler to the end, you should just have a meffler shop weld an apexi n1 muffler onto a pipe. it would be much cheaper than getting a kazuma and modding it so it was quiet. try the link if you want to hear it, but keep in mind that it doesnt do justice to how loud it is...http://www.angelfire.com/sd/jayad/Exhaust.html