TZ : Perfect for endurance racing and low speed tracks, which requires acceleration power.
26,500 rpm
500 gr/cm torque
Stand Up Brush
RZ : Perfect for sprint racing and high-speed tracks, which require maximum top speed.
27,500 rpm
500 gr/cm torque
Lay Down Brush
My secret tips : use hard springs ( It's already installed ) and Silver Brush, and gear it to 5.5 - 5.6
I don't know about BZ.