Picture of Nismo GT Titanium Shift Knob Part Number 32865-RN013. The Sentra uses a 10mm diameter shifter stick. Do not get the 12mm version. That is meant for 6-speed gearboxes.
Comparison with stock shift knob
Close up pix of knob installed. Looks like a Honda Type Aaaarrrrr shift knob if you ask me. Much much better looking than the stupid stock plastic afterthought shift knob though. Would prefer it to be slighly larger diameter as I have a pretty big left hand being a lefty.
The downsides? Well apart from the horrendous cost of anything Titanium the shift knob is made from a metal. This means that it will conduct heat better. The knob can feel cold in the early morning and I don't think you want to hold immediately it if the stupendous Malaysian sun happens to be heating it up all day.