what is the best o2 sensor for 15 road glide and autotune. i am running the 2n1 razor python exhaust with fp3. i am losing power and alot of backfire. what can i do the fix this.

 

The one that came with your bike? Sounds like your map needs tweaking.

 

very nice bike too, doing work on mines now, cant wait to get her back.

 

FP3 is designed to use the stock 02 sensors, so unless you damaged them during the pipe install, they should be fine. Ensure the 02 sensor with the black connector is hooked to the rear cylinder's pipe, and the sensor with the grey connector hooked to the front. This is the most common issue, followed by breaking the 02 sensor wires during removal/installation from old pipe to new.