Just went outside to do play some frequency sweeps and sine waves. Looks like I do have the rattle which starts to become audible right around 50 Hz. I also did check the lower end of the spectrum and output of the SWS is pretty strong at 31 Hz. You can still feel it but not hear too much at 25 Hz and at 20 Hz its pretty much non-existent. I was thinking about doing a subsonic filter to cut off the output under 35 Hz but for now I think I'll leave it alone.
I'm hoping to do some extensive tuning on Monday and maybe even play with time alignment.