Singing and Nasal Surgery
The answer to your question depends on you to a certain degree.
While septoplasty or rhinoplasty will typically affect your nasal resonance, the change is often imperceptable to others. If a change were to occur, most singers feel that it is a positive one. Having more air flow through the nose tends to open up the resonance, reduce effort, and can help with upper register as well.
HOWEVER, if you are known for having a voice with a more closed nasal resonance, then the surgery...