Installed this in my 04 Mini Cooper S non-HK OEM stereo with an aftermarket Alpine Powerpack KTP445U. This 8" tube from MTX was engineered to deliver punchy bass without breaking your bank account. It is loud and not too boomy, exactly what a nice music should be. What a difference it made!
My settings are 10 o'clock gain & 75 Hz LPF (about 9 0'clock position) using Hi level line from the Alpine powerpack that is also in 9:00 gain setting.
There is however a little soft noise (hum) when music is not being played if you pay attention to it.