well contrary to what some might say, i put the apex'i n1 single on my car 3 weeks ago, it is not loud at all, the dunk exaust is not a cat back system so if you wnat good gains you should get a custom cat back, or just go with a full system, hks hiper, n1, tanabe etc
you could talk to chris @ executivecleancar, he had a dunk canister on his ka-t, he might be able to give you some info on it.hope that helped <img src="http://www.zilvia.net/f/iB_html/non-cgi/emoticons/confused.gif" border="0" valign="absmiddle" alt='???'>