I installed the HT fairing lower speaker kit w/amp and wired it the "rear" speakers using the 70169-06 harness and had the HK radio set-up for four speakers so there was a fader control. My bike had the HK radio and Hogtunes tweeter pod already installed, along with Infinity 6.5" speakers and Dragonfly adapter rings.
Even with the fader control (allowing the front and rear speakers to be adjusted) and the amp for the lower speakers, I couldn't hear distinctly the fairing lower speakers while running down the road, and whatever sound they were delivering was negligible to me.
Subsequently, I added the Arc 125.2 amp (and removed the HT amp) and wired the fairing and fairing lower speakers in parallel (no fader control) and couldn't distinctly hear the lower speakers unless the fader basically shut off the fairing speakers. I removed the kit and sold it.
I may try fairing lower speakers again using the SESG2 fairing lower speaker boxes that use 6.5" speakers when a strong 4-channel amp that mounts inside the fairing becomes available and the fader control on the HK can be used.
To be fair, the Hog Pod tends to dominate sound so a bike without the pod may allow the rider to hear the faing lower speakers more than what I experienced.
In my case, the HT fairing lower speakers were not effective in delivering more sound while riding.
Carl