im happy with the Z's stock knob, the height, and the action of the stock shifter so not sure if i will be changing the knob on my car.
the G35C's stock knob was light, shifter was notchy so i bought the weighted TWM knob, raised the height of the knob by about 1". it feels great.
the MOMO boot i got locally for like $70, but im sure you can find them cheaper online.