I installed this because I was concerned about the different levels of bass that change from song to song. I used a Peripheral PRC1 line level controller. They are $15 on ebay. All I did was remove the volume pod from the mounting box it comes in. Then I removed the center dash by by grabbing between the inside of the 2 air vents pulling up and back. I found center and drilled 1/4" hole and mounted the volume knob.

 

It does help.. i had a bass controller that came with my amp, and I was glad I had it.. Different songs need different levels...