That case is very well cooled. If you get a less cooled case, you may end up with a even louder system. By the way, the case, doenst make noise, what makes noise are the case fans and your hardware fans.
So I suggest you exchange the fans, take a look at www.silenx.com
and possibly get a watercooled system www.koolance.com or www.swiftech.com
a nice place to find the items www.frozencpu.com
If you want to look at another cases, www.bitfenix.com