Here's the pic from the Ballast and tower owners manual. There are two different SX ballast systems, one has four pumps, one has two. Mine is the later, two pump system shown in Fig 10. It is much simpler, I prefer it. In a perfect world, that thing should fill and empty in 4.36 min. It won't with the small valve, I may even change the drain pump to a 2k, it will help both ways. 1" valves are a must. Hopefully, I won't run out of room!
Cal, you have gobs more room under the dash than I do. Pull the panel, remove the plastic frame that supports the panel (screws into the floor. Build a box to fit that huge space, a 12w7 is no problem. You can mount the heater box to it or to the hull. I cut a square of carpet away, and liquid nails, I glue a piece of MDF to the hull. I then screw a carpeted home depot cutting board cut to the right size with access holes drilled in it to the MDF block. Them, mount whatever you want to the board.
I can give you the dimensions of the box I built for the 12, take pics etc. It had a w6 in it, but a w7 would require a double thickness of 3/4" MDF, so it would be a bit larger. Plenty of room even if you mount the panel in the stock space, you can even bring it out quite a bit for more room. I had a huge 6 ch. line driver, relays for lights and pumps under there, that sub, still plenty of room for more.
