I have a 08 street glide and want to put on 10 Ape hangers

Will I need wire Throttle by wire extensions or can I just lengthen the wire .

 

I can't really say for sure, but if you have throttle by wire I would think if you're using the same gauge wire you should be able to. I wouldn't just do a butt splice tho. I would put some heat shrink tube on and solder the splices together, tape it, then use the heat shrink tube around the splice and lightly hit it with a propane torch or cigar lighter if you don't have a torch. Don't apply the heat directly but fan it so you don't burn the wires.

 

Should have plenty of spare length in the nacelle, no extensions needed. Just be very careful to not damage the sensor.
You will, however need extended clutch, brake and switch wires.