Those temps aren't bad...... They are actually very good given the size of the case and heatsinks used I would be suspect of what program your using to measure these temps. A new cpu cooler wouldn't change much you would need a thermalright true 120 extreme to see a worthy jump but that cooler wouldn't fit in your case
. What programs are you using to get those temps? Have you changed the case fans at all?
If you want something to do now make sure the cables are nicely organised and tucked ou of sight so that the airflow can be maximised.