what size fans do you need? Generally larger diameter fans spin slower to move the same air which lets them be quieter. Try to stay away from 80mm fans if you can as they have to spin at very high RPMs
why do you have the fans in a HAF 932 on high? I would expect the HAF series to provide a ton with them on medium, is it getting too hot when its on medium because i imagine its like NASA's wind tunnel in your case with everything up to high.
230mm's will be a bit trickier to find as the HAF 922 and 932 are the only cases i know that use them. SilentPCReview has some fan roundups from a few years ago but i havent been able to find a good up to date one of 120mm fans.