Wow... what to say... I have one of my own custom made five strings equipped with two EMG 40 J's, the full BQS system, a PA-2 preamp booster, and 18v power.
There is absolutely NO shielding whatsoever in the cavities, and it's the quietest bass I own!
I really wanted to try an EMG P-bass pickup in one of my basses. Even though I have been moving away from active pickups in my new builds... This experiment has amazed me. The output of this pickup is beyond strong. I had a bit of trouble dialing it in on a gig switching to a passive jazz bass! The fidelity and extended upper frequency response of it actually makes the treble cut tone control usable! I like it so much, I bought another one!