100Ω and High-speed data lines
A transistor with excess base current will be driven very hard into saturation. Because of this, the transistor will become very slow because it takes some time for the transistor to come out of saturation. A small signal transistor like an BC807 can switch 15V in a few nano seconds if you avoid saturation. (A Baker clamp might help.)

You should also try to avoid stressing the PIC by driving a transistor without a base resistor. The DIE of the PIC might become hot and fail early. The PIC not being able to supply enough base current to damage the transistor doesn't mean you should clamp it 0.7V above GND. Doing so might also trigger other effects on the IO pin. (I'm thinking about cross-conduction somewhere in the back of my mind. But the full picture doesn't show up.)

You might be better of using small signal MOSFETS instead of transistors.

Regards