Do you have a 80x80 fan? This cuold give you more CFM with less RPM.
Also, try to improve the airflow of your case. At least have one front fan inflow and one back fan outflow. Rounded cables will also help.
Finally, don't worry if temps go up a little bit as far as your computer don't lock up or crash. Temps until 60º are not rare, specially if you are in a hot region. In my case now it's summer and temps above 30º are usual, making my 1.2 Tbird going up to 55º quite easily.
Hope this helps.
DIY: read, buy, test, learn, reward yourself!